Lisle 59800 Serpentine Belt Tool This tool is used to remove and install belts on serpentine belt systems using the spring loaded idler pulley Fits idler pulleys requiring 13 mm, 14 mm, 15 mm, 16 mm, 18 mm, 19 mm hex and both 3/8 inch and 1/2 inch square drive sizes For applications with limited access, 13 mm and 16 mm sockets are built into the handle Comes with extension for hard-to-reach idler pulleys Eight low profile sockets and extension help to fit into tight spots