Fits Model A and Model B Engines. Heavy steel plate with a rubber surface bolts to the deck of the block, the other plate bolts to the water in let. Allows you to pressurize the coolant chamber of the block so you can determine if you have any cracks. Pressure gauge included. You will have to add your own 1/4" male air hose connector to pressurize using your air compressor. U.S.A. See installation instructions below for more information.