This tool provides the necessary leverage and clearance required in engine bays with minimal clearance to release the tension on Serpentine Belts with spring-loaded idler pulleys. Fits idler pulleys requiring a 15mm, 16mm and 18mm hex socket or 3/8'' and 1/2'' square drives. Also includes 13mm, 14mm and 15mm crowfoot wrenches. Manufactured from heavy-duty, alloy steel for durability and finished with black oxide to resist corrosion. Priced right for addition to any tool box.