Clever tool makes it easy to compress the valve springs to ease the removal of the rocker shaft. Just mount it into one of the valve cover screw holes and then give the knob a couple of turns to compress the valve spring. That will take the pressure off the rocker arm and allow you to easily remove the rocker shaft. Combine this with the Piston Pin Removal Tool and really save time on your next cylinder swap. Set of two (2) compression tools included. 1 lbs (0.5Kg) shipping weight.