This wrenches slip onto this filter housing to aid in the replacement of filter cartridges,easy for using. For all standard 10inch water filter housings. For strong membranes cup design to cracking. Produced of premium Component,strong & long for time service. Tighten specific law on the first hand clockwise filter bottle,so a half turn with a wrenches to normal tightness filter Bottle and filter Covers should have 1-2 mm Covers.