Newest On/Off w/purge is used in between your bottom line ASA and your tank. Easy to use with a twist to turn outside ring. Say goodbye to those hard to thread tanks once they start to air up. Use on virtually any marker. small profile prevents thread damage due to early tank air up "hard to thread on condition", normal with standard bottom line ASA's rotate the outside ring to off, purges the marker lines for easy tank removal. Use on any marker that has a fixed asa, Spyders, Tippmanns bacially anything...