Silca Aluminum Disc AdaptorThreads into any Schrader pump headCan only be used to inflate Presta valvesExclusive CompressionHead design can tighten gasket over 200% by simply tightening capCompressionHead allows adjustment to fit even the most worn presta valvesTrue no-holding disc inflation on ALL style Presta valves including threaded stemsFull metal construction, no plastic parts to wear or failUses SILCA 252 Elastomeric internal gasketWill not blow off even at pressures over 150psi