【Note:】 Specifically designed to fit Milwaukee type 3/8" cordless impact wrench Does not fit DeWalt or other cordless tools 【How to Install New O-Ring:】 Step 1: Install new o-ring to your wrench Step 2: Put retaining ring into install tool recess Step 3: insert the anvil into the retaining ring with 45 thrust Step 4: Push and bring the anvil perpendicular 【High Quality:】 The o-ring is made of high-quality rubber, which is not easy to break; the retaining rings is made of carbon steel, which is wear-resistant 【Package Includes:】 10 Sets 3/8" Impact Wrench Retainer rings & O-ring and 1Pc Anvil Retaining Ring Install Tool