The trapezoidal shape is said to eliminate the possibility of the O-ring popping out, unlike standard round-shape O-rings that rely on being pinched by the groove retaining ring for seal retention. The O-ring's design provides consistently positive retention in the groove and creates a larger overlap between the groove lip and trapezoidal seal for increased retention. Other advantages of the Trap-Seal include reduced risk of seal damage and leakage, smoother preassembly process, interchangeability with O-rings in standard SAE J1453 half-dovetail groove, and same material and hardness as the company's standard 90 Durometer nitrile O-ring.

Parker Hannifin Corp., Tube Fittings Div., 3885 Gateway Blvd., Columbus, OH 43228, (614) 279-7070,