Gauge will register the total percentage of leakage  past the rings , head gasket , intake and exhaust  valves. With an air source of 70 to 160 psi. , this  system will pressurize the cylinder with 60 psi. of  air. Designed to check the amount of cylinder  leakage in a 4-stroke engine. Speeds up  troubleshooting & helps to isolate bad components .  10 , 12 & 14mm spark plug thread hoses ,  regulator and gauge included .