Specification Brand : Mr O-Ring BulletPoint1 : Contoured Backup Ring made of Buna-N (Nitrile, NBR) for use with a variety of fluids and hydrocarbons BulletPoint2 : Durometer (hardness) of 90A BulletPoint3 : For use across a wide temperature range from -40 degrees F (-40 degrees C) to 212 degrees F (100 degrees C) BulletPoint4 : Backup Rings provide added extrusion resistance in high pressure sealing situations BulletPoint5 : 1 or 2 Backup Rings can be used per 1 O-ring, depending on the direction of pressure in the sealing application Color : Black ExternallyAssignedProductIdentifier1 : 604267398490 ExternallyAssignedProductIdentifier2 : 0604267398490 ItemDisplayDimensions_Length : 4 inches ItemName : 355 Buna-N Backup Ring, 90A Durometer, 5.278" ID, 0.183" Thick, Black (Pack of 5) ItemPackageDimensions_Height : 0.25 inches ItemPackageDimensions_Length : 4 inches ItemPackageDimensions_Width : 6 inches ItemPackageQuantity : 1 ItemTypeKeyword : o-ring-seals Manufacturer : Small Parts Material : Buna-N ModelNumber : AZ-N8-90-355/5 NumberOfItems : 5 NumberOfPieces : 30 PartNumber : AZ-N8-90-355/5 ProductDescription : Description: This convex type seal ring washer is made of silicone material, round shape, easy to install. Heat resistant,oil resistant Sealing Ring. Widely used in bathroom product, valve, faucet, bearing, hydraumatic, pump, home appliance, toy, electric motor, etc.