4259-366Y MINNESOTA RUBBER QUAD RING

Part number HQ4259 is an AS568-259 black Buna-N (Nitrile) 70 Shore A Quad-Ring measuring an inside diameter of 6.234 in (158.34 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 6.512 in (165.4 mm). A quad-ring delivers lower friction and better sealing stability than a comparable round-section o-ring.

It resists greases and lubricants, many alcohols, and water. That behavior comes from the compound itself: Buna-N (Nitrile) is known for strong abrasion and tear resistance, reliable performance in both static and dynamic service. The material carries a published service range of -40°F (-40°C) to 250°F (121.1°C). The profile itself contributes lower compressive load required to achieve a seal and resistance to the spiral twisting that defeats round-section rings.

You will find this material specified across automotive, fluid power, and hydraulic and pneumatic systems.

This item is sold individually under part number HQ4259. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.