The Exalt Fill Nipple Cover has ultra-rugged moUlded construction paired with ergonomic, intelligent design. The cover stands clear of fill hose when removed, integrated retaining ring keeps it close and in position for quick attachment. Low-profile, rubber design prevents the fill nipple from digging into your wrist. Internal seal fit keeps dirt and debris out to keep your tank and marker o-rings safe. Will not fit First Strike / Guerilla Air "SHORT" style tank regulators.