The 66785 Manual Piston Ring Filer is a high quality tool made of durable aluminum that replaces Part Numbers 66785 and 66786. Featuring a 120 grit grinding wheel, this tool allows users to quickly and accurately file piston rings to meet the manufacturer's specification. By using a feeler gauge, the user can ensure the correct piston ring end gap, resulting in optimal engine performance. Say goodbye to guesswork and achieve precision with the 66785 Manual Piston Ring Filer.