4378-366Y MINNESOTA RUBBER QUAD RING

Part number HQ4378 is an AS568-378 black Buna-N (Nitrile) 70 Shore A Quad-Ring with an inside diameter of 10.475 in (266.07 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 10.895 in (276.73 mm). A quad-ring delivers lower friction and better sealing stability than a comparable round-section o-ring.

Buna-N (Nitrile) is specified here for economical choice for high-volume maintenance programs, reliable performance in both static and dynamic service. The material holds up against petroleum-based oils, greases and lubricants, and many alcohols. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C). Verify compatibility before use with ozone and direct sunlight or automotive brake fluid. The profile itself contributes a parting line located away from the sealing surface and lower compressive load required to achieve a seal.

Maintenance and OEM teams specify it across fluid power, automotive, and construction equipment.

Reference part number HQ4378 when ordering; the item is sold individually. Check the compound against your process media, pressure and temperature before committing to a design.