Isky Racing Cams Groove-O-Matic Tool is a cylinder block O-ringing tool that can save both time and money when adjusting cylinder bore is desired. Each Groove-O-Matic Tool is easily adjustable for both diameter and depth of cut for the copper 0-ring groove. The Groove-O-Matic helps alleviate blown head gaskets on supercharged, turbocharged or hi-compression engines and is very handy for any shop or home garage.