We've used the Park CT 3 Chain Tool for decades, and it's a shop essential. The beauty of Park's professional screw type chain tools is that they last forever. The only maintenance or repair that they'll ever require is the occasional replacement of the drive pin. This Replacement Pin will fit the CT 1, CT 2, CT 3, CT 5, and CT 7 chain tools. For reference, the CT 3 has long been their professional model with a black alloy handle and blue T grip and the CT 5 is the Mini Chain Brute. The Park Chain Tool Replacement Pin screws directly into the drive mechanism of the tool. Park recommends that you install a new pin with blue Loctite to keep it secure. Once installed, a new pin will give you a long service life and prevent damage to the outer plates on your chain.