MTD shear pins for 300/500/600 Series (made in and after 2005) 2-stage snow blowers help protect a snow blower from damage when the impeller comes in contact with a solid object. Includes 4 shear pins and 4 clips. Stage: 2-Stage Length: 1-1/2 In. Warning: Cancer and Reproductive Harm - www.P65Warnings.gov -