The Performance Tool W89716 Serpentine Belt Tool is a 16-piece set designed to easily remove and install belts on serpentine systems with spring-loaded idler pulleys. It includes multiple hex and drive sizes, fitting pulleys requiring 13mm, 14mm, 15mm, 16mm, and 18mm hex sizes, as well as both 3/8 and 1/2 square drive sizes. Two extensions can be bolted on for hard-to-reach areas, making it easier to work on your engine. The set is compatible with Chrysler 2.5, 3.0 L, Ford 1.9, 2.3 L, 4.6 L, and GM 3.1 L engines, and includes a GM Fan Clutch Wrench attachment designed to loosen and tighten fan clutches on 1996 and later GM trucks and vans. Its unique design works with both 10mm and 13mm pulley bolts.