Includes air regulator, 0 - 100 psi pressure gauge, plugs for water and oil cooled oil pumps, gasket and needed hardwareThe spring tension can be adjusted to achieve the desired pop off psiAllows the engine builder to know what psi the relief valve opensMade in the USAOnly fits Feuling™ oil pumps, will not work with factory Harley-Davidson oil pumps. Fits '17-'24 M8.Proper relief valve seal will insure good hot idle oil psi and reduce oiling system cavitation and related pressure issues.