The Lang LNG-TU15-53 Tools TU-15-53 Diesel Compression Test Set is a must-have tool for technicians and mechanics working on diesel engines This set includes a compression tester, a gauge, and a manual The compression tester is used to measure the compression of a diesel engine The gauge is used to measure the pressure of the air/fuel mixture in the engine The manual provides instructions on how to use the compression tester and gauge