Drill & Tap Set - 1/8" Tapered Pipe Tap and Drill Set. If your vehicle’s axle breather hole is to small for the 1/8" fitting included and required to install the PCP Diff Cleaner. This drill and tap kit will open it up to a 1/8" pipe tap. Kit includes 1 tap drill, 1 1/8" pipe tap (NPT) and instructions.