This is an authentic manufacturer made replacement part which is specially designed for use with Yard Machines, MTD, Troy-Blit, and Yard-Man snowblowers. When the recoil starter handle is pulled, the starter rope rotates the starter pulley causing the engine turn fast enough to generate a spark to ignite the fuel in the chainsaw. This par...Read moret is made of durable plastic and is sold individually. For instillation you will need a screw driver and a pair of needle nose pliers.