The Exalt Fill Nipple Cover has ultra-rugged molded 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 orings safe. Will not fit First Strike / Guerilla Air "SHORT" style tank regulators.