Quick-Lock fittings are becoming more popular as the distribution tubing can more easily be removed and the fitting can be re-used. They are similar to the insert fitting but have an external locking nut that needs to be tightened to get a secure connection. Simply loosen the nut if the tubing needs to be removed. Quick-Lock fittings are available as couplings, tees, elbows, plugs, and hose adapters.