OTC 5039 Charged Air Cooler Tester for Class 7 and Class 8 Trucks Easy way to find air leaks in the charged air cooler systems Used on class 7 and 8 class truck engines Large 2-1/2" 0-60 PSI pressure gauge Includes regulator and relief valve and two safety cables Quick disconnect air fittings that attach to a 3" 3-1/2" or 4" cooler hose