The ULlisted fasteners provide maximum gas and liquid sealing to 20,000 psi. The devices have a preassembled silicone O-ring embedded under the head in an asymmetrical groove that permits controlled compression and maximum reusability. The fasteners are available in machine screws, bolts, nuts, rivets, and self-sealing oversize washers.

APM Hexseal, 44 Honeck St., Englewood, NJ 07631, (800) 498-9034,

Self-Sealing and Self-Locking Fasteners