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90A Durometer Urethane Back-Up Rings -128 Dash Size, Per Pack

Description & Features

Manufactured by Hercules Sealing Products, these 90A durometer urethane back-up rings are engineered for superior extrusion resistance in hydraulic applications. Designed with a dash size of -128, they provide a reliable seal by returning to their original size after installation. The urethane construction ensures performance within a temperature range of -65°F to 220°F, making them suitable for a wide range of industrial environments.

These back-up rings are specifically molded for durability and ease of installation. They fit O-Ring sizes accurately, ensuring optimal functionality in hydraulic systems. Each pack contains 8 rings, designed for long-lasting use under demanding conditions.

SKU: 575-128

Supplier Part Number (MPN): 575-128

Alternate Part Numbers: C1BU27, MI-01260354, MINO-00407X80024

Specifications

Alternate Part Numbers Alternate Part Number C1BU27, Alternate Part Number MI-01260354, Alternate Part Number MINO-00407X80024	Dash Size -128	Brand Hercules Sealing Products	Brand Hercules Sealing Products	Pack Size 1.00	UOM EA	Package Qty. 8	Supplier Part Number 575-128	Type Urethane	Product Weight 0.01 lbs

Similar Products

Model Number	Dash Size	Type	Package Qty.
575-014 90A Urethane Back-Up Ring	-014	Urethane	10
575-038 90A Urethane Back-Up Ring	-038	Urethane	10
575-212 90A Urethane Back-Up Ring	-212	Urethane	9
575-214 90A Urethane Back-Up Ring	-214	Urethane	9
575-217 90A Urethane Back-Up Ring	-217	Urethane	9
575-228 90A Urethane Back-Up Ring	-228	Urethane	10
575-231 90A Urethane Back-Up Ring	-231	Urethane	7
575-232 90A Urethane Back-Up Ring	-232	Urethane	7
575-236 90A Urethane Back-Up Ring	-236	Urethane	6
575-244 90A Urethane Back-Up Ring	-244	Urethane	4
575-252 90A Urethane Back-Up Ring	-252	Urethane	3
575-256 90A Urethane Back-Up Ring	-256	Urethane	2
575-329 90A Urethane Back-Up Ring	-329	Urethane	8
575-334 90A Urethane Back-Up Ring	-334	Urethane	7
575-338 90A Urethane Back-Up Ring	-338	Urethane	7
575-342 90A Urethane Back-Up Ring	-342	Urethane	5
575-346 90A Urethane Back-Up Ring	-346	Urethane	4
575-358 90A Urethane Back-Up Ring	-358	Urethane	2
575-011 90A Urethane Back-Up Ring	-011	Urethane	10
575-012 90A Urethane Back-Up Ring	-012	Urethane	10
575-015 90A Urethane Back-Up Ring	-015	Urethane	10
575-016 90A Urethane Back-Up Ring	-016	Urethane	10
575-017 90A Urethane Back-Up Ring	-017	Urethane	10
575-018 90A Urethane Back-Up Ring	-018	Urethane	10
575-020 90A Urethane Back-Up Ring	-020	Urethane	10
575-021 90A Urethane Back-Up Ring	-021	Urethane	10
575-022 90A Urethane Back-Up Ring	-022	Urethane	10
575-029 90A Urethane Back-Up Ring	-029	Urethane	10
575-030 90A Urethane Back-Up Ring	-030	Urethane	10
575-110 90A Urethane Back-Up Ring	-110	Urethane	9
575-111 90A Urethane Back-Up Ring	-111	Urethane	9
575-112 90A Urethane Back-Up Ring	-112	Urethane	9
575-113 90A Urethane Back-Up Ring	-113	Urethane	9
575-114 90A Urethane Back-Up Ring	-114	Urethane	9
575-115 90A Urethane Back-Up Ring	-115	Urethane	9
575-116 90A Urethane Back-Up Ring	-116	Urethane	9
575-117 90A Urethane Back-Up Ring	-117	Urethane	9
575-118 90A Urethane Back-Up Ring	-118	Urethane	9
575-119 90A Urethane Back-Up Ring	-119	Urethane	9
575-120 90A Urethane Back-Up Ring	-120	Urethane	8
575-121 90A Urethane Back-Up Ring	-121	Urethane	8
575-122 90A Urethane Back-Up Ring	-122	Urethane	8
575-124 90A Urethane Back-Up Ring	-124	Urethane	8
575-125 90A Urethane Back-Up Ring	-125	Urethane	8
575-126 90A Urethane Back-Up Ring	-126	Urethane	8
575-127 90A Urethane Back-Up Ring	-127	Urethane	8
575-128 90A Urethane Back-Up Ring	-128	Urethane	8
575-129 90A Urethane Back-Up Ring	-129	Urethane	8
575-132 90A Urethane Back-Up Ring	-132	Urethane	8
575-133 90A Urethane Back-Up Ring	-133	Urethane	8
575-135 90A Urethane Back-Up Ring	-135	Urethane	8
575-136 90A Urethane Back-Up Ring	-136	Urethane	8
575-137 90A Urethane Back-Up Ring	-137	Urethane	8
575-140 90A Urethane Back-Up Ring	-140	Urethane	10
575-141 90A Urethane Back-Up Ring	-141	Urethane	7
575-145 90A Urethane Back-Up Ring	-145	Urethane	6
575-149 90A Urethane Back-Up Ring	-149	Urethane	6
575-151 90A Urethane Back-Up Ring	-151	Urethane	6
575-154 90A Urethane Back-Up Ring	-154	Urethane	3
575-155 90A Urethane Back-Up Ring	-155	Urethane	3
575-157 90A Urethane Back-Up Ring	-157	Urethane	3
575-208 90A Urethane Back-Up Ring	-208	Urethane	10
575-209 90A Urethane Back-Up Ring	-209	Urethane	9
575-210 90A Urethane Back-Up Ring	-210	Urethane	9
575-211 90A Urethane Back-Up Ring	-211	Urethane	9
575-213 90A Urethane Back-Up Ring	-213	Urethane	9
575-215 90A Urethane Back-Up Ring	-215	Urethane	9
575-216 90A Urethane Back-Up Ring	-216	Urethane	9
575-218 90A Urethane Back-Up Ring	-218	Urethane	9
575-219 90A Urethane Back-Up Ring	-219	Urethane	9
575-220 90A Urethane Back-Up Ring	-220	Urethane	10
575-221 90A Urethane Back-Up Ring	-221	Urethane	10
575-222 90A Urethane Back-Up Ring	-222	Urethane	10
575-223 90A Urethane Back-Up Ring	-223	Urethane	8
575-224 90A Urethane Back-Up Ring	-224	Urethane	8
575-225 90A Urethane Back-Up Ring	-225	Urethane	10
575-226 90A Urethane Back-Up Ring	-226	Urethane	10
575-227 90A Urethane Back-Up Ring	-227	Urethane	10
575-229 90A Urethane Back-Up Ring	-229	Urethane	10
575-230 90A Urethane Back-Up Ring	-230	Urethane	7
575-233 90A Urethane Back-Up Ring	-233	Urethane	7
575-234 90A Urethane Back-Up Ring	-234	Urethane	6
575-235 90A Urethane Back-Up Ring	-235	Urethane	6
575-237 90A Urethane Back-Up Ring	-237	Urethane	5
575-238 90A Urethane Back-Up Ring	-238	Urethane	5
575-239 90A Urethane Back-Up Ring	-239	Urethane	5
575-240 90A Urethane Back-Up Ring	-240	Urethane	5
575-241 90A Urethane Back-Up Ring	-241	Urethane	5
575-242 90A Urethane Back-Up Ring	-242	Urethane	5
575-243 90A Urethane Back-Up Ring	-243	Urethane	5
575-245 90A Urethane Back-Up Ring	-245	Urethane	4
575-246 90A Urethane Back-Up Ring	-246	Urethane	3
575-247 90A Urethane Back-Up Ring	-247	Urethane	3
575-248 90A Urethane Back-Up Ring	-248	Urethane	3
575-249 90A Urethane Back-Up Ring	-249	Urethane	3
575-253 90A Urethane Back-Up Ring	-253	Urethane	3
575-254 90A Urethane Back-Up Ring	-254	Urethane	3
575-255 90A Urethane Back-Up Ring	-255	Urethane	2
575-258 90A Urethane Back-Up Ring	-258	Urethane	2
575-259 90A Urethane Back-Up Ring	-259	Urethane	2
575-260 90A Urethane Back-Up Ring	-260	Urethane	2
575-261 90A Urethane Back-Up Ring	-261	Urethane	2
575-262 90A Urethane Back-Up Ring	-262	Urethane	2
575-314 90A Urethane Back-Up Ring	-314	Urethane	8
575-316 90A Urethane Back-Up Ring	-316	Urethane	8
575-321 90A Urethane Back-Up Ring	-321	Urethane	8
575-324 90A Urethane Back-Up Ring	-324	Urethane	8
575-325 90A Urethane Back-Up Ring	-325	Urethane	8
575-326 90A Urethane Back-Up Ring	-326	Urethane	8
575-327 90A Urethane Back-Up Ring	-327	Urethane	8
575-328 90A Urethane Back-Up Ring	-328	Urethane	8
575-330 90A Urethane Back-Up Ring	-330	Urethane	8
575-331 90A Urethane Back-Up Ring	-331	Urethane	8
575-332 90A Urethane Back-Up Ring	-332	Urethane	8
575-333 90A Urethane Back-Up Ring	-333	Urethane	8
575-335 90A Urethane Back-Up Ring	-335	Urethane	7
575-336 90A Urethane Back-Up Ring	-336	Urethane	7
575-337 90A Urethane Back-Up Ring	-337	Urethane	7
575-339 90A Urethane Back-Up Ring	-339	Urethane	6
575-340 90A Urethane Back-Up Ring	-340	Urethane	6
575-341 90A Urethane Back-Up Ring	-341	Urethane	6
575-344 90A Urethane Back-Up Ring	-344	Urethane	4
575-345 90A Urethane Back-Up Ring	-345	Urethane	4
575-347 90A Urethane Back-Up Ring	-347	Urethane	4
575-348 90A Urethane Back-Up Ring	-348	Urethane	4
575-349 90A Urethane Back-Up Ring	-349	Urethane	3
575-350 90A Urethane Back-Up Ring	-350	Urethane	3
575-425 90A Urethane Back-Up Ring	-425	Urethane	3
575-427 90A Urethane Back-Up Ring	-427	Urethane	3
575-429 90A Urethane Back-Up Ring	-429	Urethane	3
575-432 90A Urethane Back-Up Ring	-432	Urethane	2
575-433 90A Urethane Back-Up Ring	-433	Urethane	2
575-434 90A Urethane Back-Up Ring	-434	Urethane	2
575-436 90A Urethane Back-Up Ring	-436	Urethane	2
575-439 90A Urethane Back-Up Ring	-439	Urethane	2

Product Questions & Answers (1)

Question by: Dean S on Jul 20, 2025, 7:45 AM

these stretch over the o-ring groove for install or do they sit separate from it? asking cause I don't wanna force something that ain't supposed to be forced

Answer by: Customer Support on Jul 22, 2025, 7:21 AM

Urethane back-up rings like these are meant to be stretched during installation, then they snap back to their original shape once seated. That stretch-and-return behavior is actually what makes them easier to work with compared to rigid alternatives. They sit alongside the O-ring in the groove, not over it, and the sizing corresponds directly to standard O-ring dash sizes, so a -128 back-up ring pairs with a -128 O-ring.