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(S66-6-4) COMP/FEM CONN 3/8X1/4

Description & Features

Manufactured by Midland Industries, the (S66-6-4) Comp/Fem Conn 3/8x1/4 is a compression-to-female connector designed to transition between a 3/8" compression fitting and a 1/4" female thread. This type of fitting is commonly used in instrumentation, fluid control, and industrial tubing systems where a secure, leak-resistant connection between dissimilar thread or tube sizes is required.

The connector's compression end grips tubing mechanically, eliminating the need for soldering or flaring, while the female threaded end provides a straightforward threaded attachment point. Midland Industries fittings are recognized in industrial distribution for consistent dimensional accuracy and broad compatibility across standard tubing and fitting systems.

SKU: 18153

Supplier Part Number (MPN): 18153

Specifications

Brand Midland Industries	Brand Midland Industries	Pack Size 1.00	UOM EA	Supplier Part Number 18153	Product Weight 0.09 lbs

Product Questions & Answers (2)

Question by: Roy J on Dec 6, 2025, 9:53 PM

fitting's compression end, does it need any kind of sealant or thread tape on that side, or does it grip the tubing on its own?

Answer by: Customer Support on Dec 8, 2025, 10:22 AM

Compression fittings like this one work by gripping the tubing mechanically when you tighten the nut. No solder, no flaring, no tape on the compression side. The ferrule seats against the tubing and forms the seal through that mechanical bite. The female threaded end is a different story, depending on the mating fitting and the fluid being run, thread sealant on that side is generally a good idea.

Question by: Dwayne H on Feb 13, 2026, 5:18 PM

got a 3/8 inch tube line and need to hook into a 1/4 female thread port. is that what this fitting is for

Answer by: Customer Support on Feb 15, 2026, 10:29 AM

Made to bridge those two ends, it transitions from a 3/8 inch compression connection on the tubing side over to a 1/4 inch female threaded connection on the other side.