Special tool (knock-off) to remove Moen faucet cartridges. The first one I took out was brass, and I had read these might be tricky (maybe the plunger comes out can't remember). So I bought the tool and used it, and it did work. But subsequent cartridges were plastic, and they always come out easily, so never used the tool again...same with a thread chaser when I installed the Draw Tite hitch. Car was 10 years old and holes severely rusted. In that case, I used the actual bolts with WD40, and gently turned them in and out, I mean really gently. Once they did, I used the chaser thread tool, and that was the only time the set has ever been used....