Used to close off 1/2" poly tube. Very easy to use, long-lasting, heavy duty hose connectors, adapters and fittings for all your connection needs. 'PERMA-LOC' system of permanent, re-usable fitting connectors. Simply push tubing over easy to use barbed end, then hand tighten locking nut over tubing for a permanent secure fit. Just loosen lock nut, pull tube off and re-use as needed.