Description WIll not leak once locked on.Hands-free, does not release under pressure3.6? of effective reach. Perfect for greasing U-joints, harvester heads, shielded PTO shafts, and deeply recessed Zerks.Will not leak once locked on.1/8? NPT thread. Compatible with all grease guns.Works on all Zerk fittings, SAE and metric.Comes with free replacement seal and jaws. Fully rebuildable.