Putting the connecting rod through first, simply place the piston (with rings) into the tapered end of the ring compressor. Tighten the compressor snugly around the base of the piston. Then lay the compressor flat on the engine cylinder bore. NOTE: Image shows #PFM66766 and is for reference only.Pit Stop USA offers Proform Adjustable Piston Ring Compressor 4.125"- 4.205" - Gold 66767 at low everyday prices. Be sure to check out all of our products from ProForm including ProForm Piston Ring Compressors.