a separate u - shaped safety lock is provided for use with a trigger drinker utilizing a bayonet type coupler . in poultry and small animal trigger drinker watering systems the u - shaped safety lock restricts telescopically interfitting components from rotation . the lock is inserted through one component and partially surrounds a boss on a second component to prevent both clockwise and counterclockwise rotation of the components relative to one another . the safety lock can break upon reaching a pre - determined torque .