Nickel-plated carbon steel for corrosion resistance and comfortable vinyl-dipped handles. Sprung mechanism for fine control. Installs and removes piston rings up to 6.4mm (1/4") without twisting. Makes child's play of the fiddly task of fitting a piston. Place the compressor over the piston rings and tighten using the supplied 1/4" Square key. Place piston into cylinder and the compressor gives you perfect alignment making it easy to push the piston fully into place., Weight: 0.8598028218 pounds, Manufacturer: Caliwill