This oil filter wrench featrues two thick jaws which slide together using a cam mechanism to grab your filter. If you are looking for a professional quality cam-style Oil Filter Wrench, then CTA Tools has just the ticket. This filter wrench fits most filters from 3-3/8" - 3-7/8" (86mm-98mm) in outside diameter. Simply slide this wrench over your filter and use either a 3/8" square drive ratchet/breaker bar or any 7/8" wrench or socket and loosen your filter quickly and easily.