Imagine Pools H-0140 1" Diameter Pulley Wheel for 1/4" Diameter Rope The Pulley Wheel ensures smooth and proper operation of the 1/4" diameter wheel in the pool cover. Imagine pool covers are completely protective, and are designed to help the pool in its best working order for years to come. This replacement part will help ensure that the cover operates properly, and is a seamless integration to the original.