Spectre's Pulley Shim Kit is designed to help you properly space your water pump pulley for correct belt alignment. Featuring high quality aluminum construction, these shims should be used between the water pump flange and pulley. Easy to install, this kit includes three 1/16 inch shims, allowing for a thickness of 1/16 inch, 1/8 inch, or 3/16 inch. Spectre s Pulley Shim Kit is designed to help you properly space your water pump pulley for correct belt alignment. These shims should be used between the water pump flange and pulley.