Our special aluminum Stat-O-Seals are much more reliable than the more common steel version. Even if the rubber portion fails to make contact all around the port, the aluminum acts as a crush washer, providing a reliable metal-on-metal seal.
Each Stat-O-Seal has a Buna-N inner seal bonded to the center of the aluminum washer. The Buna-N rubber is resistant to water, oil, and petroleum fuels (not for use in brake systems). Use them to seal screws, bolts, or plumbing fittings. The rubber insert is molded to be slightly thicker than the washer, though not quite as thick as a standard rubber O-ring. Stat-O-Seals should not be used to replace O-rings on chamfered ports.