OTC's Charged Air Cooler Tester is the easy way to find air leaks in charged air cooler systems For use on class 7 and 8 truck engines Large, easy to read 2-1/2 inch pressure gauge reads 0-60 PSI Kit includes regulator, relief valve, and two safety cables Quick disconnect air fittings attach to 3 inch, 3-1/2 inch, or 4 inch cooler hoses