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Polyurethane U-Seal, 4.25 Inch OD, 3.75 Inch ID, 0.38 Inch Height

Description & Features

Manufactured by Hercules Sealing Products, this urethane seal is rated for pressures from 0 to 6,000 PSI and temperatures ranging from -65°F to 220°F, making it suitable for demanding hydraulic cylinder applications. The beveled lip design promotes effective film breaking across the sealing surface. The Polyurethane U-Seal, 4.25 Inch OD, 3.75 Inch ID, 0.38 Inch Height features a 0.25-inch cross section with a height of 0.375 inches, placing it in the deep type category where height exceeds the cross section. With an outer diameter of 4.25 inches and an inner diameter of 3.75 inches, this seal is sized for precise fitment in compatible hydraulic assemblies. Catalog number C1KN66 can be used as a reference when cross-referencing with manufacturer documentation.

SKU: U25-3.75-37B

Supplier Part Number (MPN): U25-3.75-37B

Alternate Part Numbers: C1KN66, MI-01810349, MINO-00407Q30123

Specifications

Cross Section 0.25 in	Brand Hercules Sealing Products	Brand Hercules Sealing Products	Pack Size 1.00	UOM EA	H 0.375 in	I.D. 3.75 in	O.D. 4.25 in	Supplier Part Number U25-3.75-37B	Alternate Part Numbers Alternate Part Number C1KN66, Alternate Part Number MI-01810349, Alternate Part Number MINO-00407Q30123	Product Weight 0.06 lbs

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U25-1.25-37B Polyurethane U-Seal	0.25 in	1.25 in	1.75 in	0.375 in
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U25-2.00-37B Polyurethane U-Seal	0.25 in	2 in	2.5 in	0.375 in
U25-2.50-37B Polyurethane U-Seal	0.25 in	2.5 in	3 in	0.375 in
U25-3.00 Polyurethane U-Seal	0.25 in	3 in	3.5 in	0.25 in
U25-3.00-37B Polyurethane U-Seal	0.25 in	3 in	3.5 in	0.375 in
U25-3.50-37B Polyurethane U-Seal	0.25 in	3.5 in	4 in	0.375 in
U25-4.00-SQB Polyurethane U-Seal	0.25 in	4 in	4.5 in	0.25 in
U25-4.50 Polyurethane U-Seal	0.25 in	4.5 in	5 in	0.25 in
U25-5.00 Polyurethane U-Seal	0.25 in	5 in	5.5 in	0.25 in
U12-0.18-25B Polyurethane U-Seal	0.125 in	0.1875 in	0.438 in	0.25 in
U12-0.25-25B Polyurethane U-Seal	0.125 in	0.25 in	0.5 in	0.25 in
U12-0.25-SQB Polyurethane U-Seal	0.125 in	0.25 in	0.5 in	0.125 in
U12-0.31-25B Polyurethane U-Seal	0.125 in	0.3125 in	0.563 in	0.25 in
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U12-0.37 Polyurethane U-Seal	0.125 in	0.375 in	0.625 in	0.125 in
U12-0.50-25B Polyurethane U-Seal	0.125 in	0.5 in	0.75 in	0.25 in
U12-0.50-SQB Polyurethane U-Seal	0.125 in	0.5 in	0.75 in	0.125 in
U12-0.56 Polyurethane U-Seal	0.125 in	0.625 in	0.938 in	0.125 in
U12-0.62-SQB Polyurethane U-Seal	0.125 in	0.625 in	0.875 in	0.125 in
U12-0.68 Polyurethane U-Seal	0.125 in	0.6875 in	0.938 in	0.125 in
U12-0.75-18B Polyurethane U-Seal	0.125 in	0.75 in	1 in	0.1875 in
U12-0.75-25B Polyurethane U-Seal	0.125 in	0.75 in	1 in	0.25 in
U12-0.75-SQB Polyurethane U-Seal	0.125 in	0.75 in	1 in	0.125 in
U12-0.81 Polyurethane U-Seal	0.125 in	0.8125 in	1.063 in	0.125 in
U12-0.87-25B Polyurethane U-Seal	0.125 in	0.875 in	1.125 in	0.25 in
U12-0.87-SQB Polyurethane U-Seal	0.125 in	0.875 in	1.125 in	0.125 in
U12-1.00-18B Polyurethane U-Seal	0.125 in	1 in	1.25 in	0.1875 in
U12-1.00-SQB Polyurethane U-Seal	0.125 in	1 in	1.25 in	0.125 in
U12-1.06-SQB Polyurethane U-Seal	0.125 in	1.0625 in	1.313 in	0.125 in
U12-1.12-25B Polyurethane U-Seal	0.125 in	1.0625 in	1.375 in	0.25 in
U12-1.12-SQB Polyurethane U-Seal	0.125 in	1.0625 in	1.375 in	0.125 in
U12-1.18 Polyurethane U-Seal	0.125 in	0.188 in	1.438 in	0.125 in
U12-1.18-18B Polyurethane U-Seal	0.125 in	0.188 in	1.438 in	0.1875 in
U12-1.18-25B Polyurethane U-Seal	0.125 in	0.188 in	1.438 in	0.25 in
U12-1.25-18B Polyurethane U-Seal	0.125 in	1.25 in	1.5 in	0.1875 in
U12-1.25-25B Polyurethane U-Seal	0.125 in	1.25 in	1.5 in	0.25 in
U12-1.37-25B Polyurethane U-Seal	0.125 in	1.375 in	1.625 in	0.25 in
U12-1.37-SQB Polyurethane U-Seal	0.125 in	1.375 in	1.625 in	0.125 in
U12-1.50-25B Polyurethane U-Seal	0.125 in	1.5 in	1.75 in	0.25 in
U12-1.50-SQB Polyurethane U-Seal	0.125 in	1.5 in	1.75 in	0.125 in
U12-1.62-SQB Polyurethane U-Seal	0.125 in	1.625 in	1.875 in	0.125 in
U12-1.75-SQB Polyurethane U-Seal	0.125 in	1.75 in	2 in	0.125 in
U12-2.00 Polyurethane U-Seal	0.125 in	2 in	2.25 in	0.125 in
U12-2.25 Polyurethane U-Seal	0.125 in	2.25 in	2.5 in	0.125 in
U12-2.75 Polyurethane U-Seal	0.125 in	2.75 in	3 in	0.125 in
U15-1.18 Polyurethane U-Seal	0.1563 in	0.188 in	1.5 in	0.1563 in
U15-1.25 Polyurethane U-Seal	0.1563 in	1.25 in	1.563 in	0.1563 in
U15-1.37 Polyurethane U-Seal	0.1563 in	1.375 in	1.688 in	0.1563 in
U18-0.50 Polyurethane U-Seal	0.1875 in	0.5 in	0.875 in	0.1875 in
U18-0.62-31B Polyurethane U-Seal	0.1875 in	0.625 in	1 in	0.3125 in
U18-0.62-SQB Polyurethane U-Seal	0.1875 in	0.625 in	1 in	0.1875 in
U18-0.75-31B Polyurethane U-Seal	0.1875 in	0.75 in	1.125 in	0.3125 in
U18-0.75-SQB Polyurethane U-Seal	0.1875 in	0.75 in	1.125 in	0.1875 in
U18-0.87-31B Polyurethane U-Seal	0.1875 in	0.875 in	1.25 in	0.3125 in
U18-0.87-SQB Polyurethane U-Seal	0.1875 in	0.875 in	1.25 in	0.1875 in
U18-1.00-25B Polyurethane U-Seal	0.1875 in	1 in	1.375 in	0.25 in
U18-1.00-31B Polyurethane U-Seal	0.1875 in	1 in	1.375 in	0.3125 in
U18-1.00-37B Polyurethane U-Seal	0.1875 in	1 in	1.375 in	0.375 in
U18-1.00-SQB Polyurethane U-Seal	0.1875 in	1 in	1.375 in	0.1875 in
U18-1.12-25B Polyurethane U-Seal	0.1875 in	1.0625 in	1.5 in	0.25 in
U18-1.12-31B Polyurethane U-Seal	0.1875 in	1.0625 in	1.5 in	0.3125 in
U18-1.12-SQB Polyurethane U-Seal	0.1875 in	1.0625 in	1.5 in	0.1875 in
U18-1.18 Polyurethane U-Seal	0.1875 in	0.188 in	1.563 in	0.1875 in
U18-1.25-25B Polyurethane U-Seal	0.1875 in	1.25 in	1.625 in	0.25 in
U18-1.25-31B Polyurethane U-Seal	0.1875 in	1.25 in	1.625 in	0.3125 in
U18-1.25-37B Polyurethane U-Seal	0.1875 in	1.25 in	1.625 in	0.375 in
U18-1.37-25B Polyurethane U-Seal	0.1875 in	1.375 in	1.75 in	0.25 in
U18-1.37-31B Polyurethane U-Seal	0.1875 in	1.375 in	1.75 in	0.3125 in
U18-1.37-37B Polyurethane U-Seal	0.1875 in	1.375 in	1.75 in	0.375 in
U18-1.37-SQB Polyurethane U-Seal	0.1875 in	1.375 in	1.75 in	0.1875 in
U18-1.50-25B Polyurethane U-Seal	0.1875 in	1.5 in	1.875 in	0.25 in
U18-1.50-31B Polyurethane U-Seal	0.1875 in	1.5 in	1.875 in	0.3125 in
U18-1.50-37B Polyurethane U-Seal	0.1875 in	1.5 in	1.875 in	0.375 in
U18-1.50-SQB Polyurethane U-Seal	0.1875 in	1.5 in	1.875 in	0.1875 in
U18-1.62 Polyurethane U-Seal	0.1875 in	1.625 in	2 in	0.1875 in
U18-1.62-25B Polyurethane U-Seal	0.1875 in	1.625 in	2 in	0.25 in
U18-1.62-31B Polyurethane U-Seal	0.1875 in	1.625 in	2 in	0.3125 in
U18-1.62-37B Polyurethane U-Seal	0.1875 in	1.625 in	2 in	0.375 in
U18-1.62-SQB Polyurethane U-Seal	0.1875 in	1.625 in	2 in	0.1875 in
U18-1.75-25B Polyurethane U-Seal	0.1875 in	1.75 in	2.125 in	0.25 in
U18-1.75-31B Polyurethane U-Seal	0.1875 in	1.75 in	2.125 in	0.3125 in
U18-1.75-SQB Polyurethane U-Seal	0.1875 in	1.75 in	2.125 in	0.1875 in
U18-1.87-37B Polyurethane U-Seal	0.1875 in	1.875 in	2.25 in	0.375 in
U18-1.87-SQB Polyurethane U-Seal	0.1875 in	1.875 in	2.25 in	0.1875 in
U18-2.00-31B Polyurethane U-Seal	0.1875 in	2 in	2.375 in	0.3125 in
U18-2.00-37B Polyurethane U-Seal	0.1875 in	2 in	2.375 in	0.375 in
U18-2.00-SQB Polyurethane U-Seal	0.1875 in	2 in	2.375 in	0.1875 in
U18-2.12-25B Polyurethane U-Seal	0.1875 in	2.125 in	2.5 in	0.25 in
U18-2.25-37B Polyurethane U-Seal	0.1875 in	2.25 in	2.625 in	0.375 in
U18-2.25-SQB Polyurethane U-Seal	0.1875 in	2.25 in	2.625 in	0.1875 in
U18-2.37-SQB Polyurethane U-Seal	0.1875 in	2.375 in	2.75 in	0.1875 in
U18-2.50-25B Polyurethane U-Seal	0.1875 in	2.5 in	2.875 in	0.25 in
U18-2.50-37B Polyurethane U-Seal	0.1875 in	2.5 in	2.875 in	0.375 in
U18-2.50-SQB Polyurethane U-Seal	0.1875 in	2.5 in	2.875 in	0.1875 in
U18-2.62-37B Polyurethane U-Seal	0.1875 in	2.625 in	3 in	0.375 in
U18-2.62-SQB Polyurethane U-Seal	0.1875 in	2.625 in	3 in	0.1875 in
U18-2.75-37B Polyurethane U-Seal	0.1875 in	2.75 in	3.125 in	0.375 in
U18-2.75-SQB Polyurethane U-Seal	0.1875 in	2.75 in	3.125 in	0.1875 in
U18-2.87 Polyurethane U-Seal	0.1875 in	2.875 in	3.25 in	0.1875 in
U18-3.00 Polyurethane U-Seal	0.1875 in	3 in	3.375 in	0.1875 in
U18-3.00-37B Polyurethane U-Seal	0.1875 in	3 in	3.375 in	0.375 in
U18-3.12-37B Polyurethane U-Seal	0.1875 in	3.125 in	3.5 in	0.375 in
U18-3.12-SQB Polyurethane U-Seal	0.1875 in	3.125 in	3.5 in	0.1875 in
U18-3.50-37B Polyurethane U-Seal	0.1875 in	3.5 in	3.875 in	0.375 in
U18-3.62-37B Polyurethane U-Seal	0.1875 in	3.625 in	4 in	0.375 in
U18-3.62-SQB Polyurethane U-Seal	0.1875 in	3.625 in	4 in	0.1875 in
U18-4.00-37B Polyurethane U-Seal	0.1875 in	4 in	4.375 in	0.375 in
U25-0.75 Polyurethane U-Seal	0.25 in	0.75 in	1.25 in	0.25 in
U25-0.93 Polyurethane U-Seal	0.25 in	0.8125 in	1.438 in	0.25 in
U25-1.00-37B Polyurethane U-Seal	0.25 in	1 in	1.5 in	0.375 in
U25-1.00-SQB Polyurethane U-Seal	0.25 in	1 in	1.5 in	0.25 in
U25-1.12 Polyurethane U-Seal	0.25 in	1.0625 in	1.625 in	0.25 in
U25-1.12-37B Polyurethane U-Seal	0.25 in	1.0625 in	1.625 in	0.375 in
U25-1.18 Polyurethane U-Seal	0.25 in	0.188 in	1.688 in	0.25 in
U25-1.25-SQB Polyurethane U-Seal	0.25 in	1.25 in	1.75 in	0.25 in
U25-1.37 Polyurethane U-Seal	0.25 in	1.375 in	1.875 in	0.25 in
U25-1.37-37B Polyurethane U-Seal	0.25 in	1.375 in	1.875 in	0.375 in
U25-1.50-31B Polyurethane U-Seal	0.25 in	1.5 in	2 in	0.3125 in
U25-1.50-SQB Polyurethane U-Seal	0.25 in	1.5 in	2 in	0.25 in
U25-1.75 Polyurethane U-Seal	0.25 in	1.75 in	2.25 in	0.25 in
U25-1.75-37B Polyurethane U-Seal	0.25 in	1.75 in	2.25 in	0.375 in
U25-1.87-37B Polyurethane U-Seal	0.25 in	1.875 in	2.375 in	0.375 in
U25-2.00-31B Polyurethane U-Seal	0.25 in	2 in	2.5 in	0.3125 in
U25-2.00-SQB Polyurethane U-Seal	0.25 in	2 in	2.5 in	0.25 in
U25-2.12-37B Polyurethane U-Seal	0.25 in	2.125 in	2.625 in	0.375 in
U25-2.25 Polyurethane U-Seal	0.25 in	2.25 in	2.75 in	0.25 in
U25-2.25-37B Polyurethane U-Seal	0.25 in	2.25 in	2.75 in	0.375 in
U25-2.37-37B Polyurethane U-Seal	0.25 in	2.375 in	2.875 in	0.375 in
U25-2.50-SQB Polyurethane U-Seal	0.25 in	2.5 in	3 in	0.25 in
U25-2.62-37B Polyurethane U-Seal	0.25 in	2.625 in	3.125 in	0.375 in
U25-2.75-37B Polyurethane U-Seal	0.25 in	2.75 in	3.25 in	0.375 in
U25-2.75-SQB Polyurethane U-Seal	0.25 in	2.75 in	3.25 in	0.25 in
U25-3.25-37B Polyurethane U-Seal	0.25 in	3.25 in	3.75 in	0.375 in
U25-3.50 Polyurethane U-Seal	0.25 in	3.5 in	4 in	0.25 in
U25-3.50-SQB Polyurethane U-Seal	0.25 in	3.5 in	4 in	0.25 in
U25-3.75-37B Polyurethane U-Seal	0.25 in	3.75 in	4.25 in	0.375 in
U25-3.75-SQB Polyurethane U-Seal	0.25 in	3.75 in	4.25 in	0.25 in
U25-4.00-37B Polyurethane U-Seal	0.25 in	4 in	4.5 in	0.375 in
U25-4.00-50D Polyurethane U-Seal	0.25 in	4 in	4.5 in	0.5 in
U25-4.00-56B Polyurethane U-Seal	0.25 in	4 in	4.5 in	0.5625 in
U25-4.50-37B Polyurethane U-Seal	0.25 in	4.5 in	5 in	0.375 in
U25-4.50-56B Polyurethane U-Seal	0.25 in	4.5 in	5 in	0.5625 in
U25-4.50-62B Polyurethane U-Seal	0.25 in	4.5 in	5 in	0.625 in
U25-5.00-37B Polyurethane U-Seal	0.25 in	5 in	5.5 in	0.375 in
U25-5.50 Polyurethane U-Seal	0.25 in	5.5 in	6 in	0.25 in
U25-5.50-37B Polyurethane U-Seal	0.25 in	5.5 in	6 in	0.375 in
U25-5.50-56B Polyurethane U-Seal	0.25 in	5.5 in	6 in	0.5625 in
U31-1.00-50B Polyurethane U-Seal	0.3125 in	1 in	1.625 in	0.5 in
U31-1.25 Polyurethane U-Seal	0.3125 in	1.25 in	1.875 in	0.3125 in
U31-1.25-37B Polyurethane U-Seal	0.3125 in	1.25 in	1.875 in	0.375 in
U31-1.37-37B Polyurethane U-Seal	0.3125 in	1.375 in	2 in	0.375 in
U31-1.37-SQB Polyurethane U-Seal	0.3125 in	1.375 in	2 in	0.3125 in
U31-1.50 Polyurethane U-Seal	0.3125 in	1.5 in	2.125 in	0.3125 in
U31-1.75-37B Polyurethane U-Seal	0.3125 in	1.75 in	2.375 in	0.375 in
U31-1.87 Polyurethane U-Seal	0.3125 in	1.875 in	2.5 in	0.3125 in
U31-2.00 Polyurethane U-Seal	0.3125 in	2 in	2.625 in	0.3125 in
U31-2.00-50B Polyurethane U-Seal	0.3125 in	2 in	2.625 in	0.5 in
U31-2.25-50B Polyurethane U-Seal	0.3125 in	2.25 in	2.875 in	0.5 in
U31-2.37 Polyurethane U-Seal	0.3125 in	2.375 in	3 in	0.3125 in
U31-2.50 Polyurethane U-Seal	0.3125 in	2.5 in	3.125 in	0.3125 in
U31-2.50-50B Polyurethane U-Seal	0.3125 in	2.5 in	3.125 in	0.5 in
U31-2.75 Polyurethane U-Seal	0.3125 in	2.75 in	3.375 in	0.3125 in
U31-2.75-50B Polyurethane U-Seal	0.3125 in	2.75 in	3.375 in	0.5 in
U31-2.87 Polyurethane U-Seal	0.3125 in	2.875 in	3.5 in	0.3125 in
U31-3.00-50B Polyurethane U-Seal	0.3125 in	3 in	3.625 in	0.5 in
U31-3.37-50B Polyurethane U-Seal	0.3125 in	3.375 in	4 in	0.5 in
U31-4.00 Polyurethane U-Seal	0.3125 in	4 in	4.625 in	0.3125 in
U31-4.00-56B Polyurethane U-Seal	0.3125 in	4 in	4.625 in	0.5625 in
U31-4.37 Polyurethane U-Seal	0.3125 in	4.375 in	5 in	0.3125 in
U31-4.50 Polyurethane U-Seal	0.3125 in	4.5 in	5.125 in	0.3125 in
U37-1.25 Polyurethane U-Seal	0.375 in	1.25 in	2 in	0.375 in
U37-1.75 Polyurethane U-Seal	0.375 in	1.75 in	2.5 in	0.375 in
U37-2.50-50B Polyurethane U-Seal	0.375 in	2.5 in	3.25 in	0.5 in
U37-2.75 Polyurethane U-Seal	0.375 in	2.75 in	3.5 in	0.375 in
U37-3.25-50B Polyurethane U-Seal	0.375 in	3.25 in	4 in	0.5 in
U37-3.50 Polyurethane U-Seal	0.375 in	3.5 in	4.25 in	0.375 in
U37-3.75-50D Polyurethane U-Seal	0.375 in	3.75 in	4.5 in	0.5 in
U37-4.00-62B Polyurethane U-Seal	0.375 in	4 in	4.75 in	0.625 in
U37-4.25-50D Polyurethane U-Seal	0.375 in	4.25 in	5 in	0.5 in
U37-4.25-62B Polyurethane U-Seal	0.375 in	4.25 in	5 in	0.625 in
U37-4.25-SQB Polyurethane U-Seal	0.375 in	4.25 in	5 in	0.375 in
U37-4.50-62B Polyurethane U-Seal	0.375 in	4.5 in	5.25 in	0.625 in
U37-5.00-62B Polyurethane U-Seal	0.375 in	5 in	5.75 in	0.625 in
U37-5.25 Polyurethane U-Seal	0.375 in	5.25 in	6 in	0.375 in
U37-5.25-50D Polyurethane U-Seal	0.375 in	5.25 in	6 in	0.5 in
U37-6.25-50D Polyurethane U-Seal	0.375 in	6.25 in	7 in	0.5 in
U50-2.00-SQB Polyurethane U-Seal	0.5 in	2 in	3 in	0.5 in
U50-2.50 Polyurethane U-Seal	0.5 in	2.5 in	3.5 in	0.5 in

Product Questions & Answers (1)

Question by: Harold R on Jun 13, 2025, 6:34 PM

got a cylinder groove set up for a 3.75 inch rod, is this u-seal the right size or am i mixing up the numbers

Answer by: Customer Support on Jun 15, 2025, 8:15 AM

For sizing, the key dimensions on this U-seal are 3.75 inch ID and 4.25 inch OD, with a 0.25 inch cross section and 0.375 inch height. If your application calls for a seal with those exact ID and OD dimensions, this one matches.