Diameter: 2.95 inches (7.5Cm) . Height : 2.17inches (5.5Cm). ayak Skeg, rubber boat air valve.Fit for most Kayak boat and river rafts.Easy to inflate and to deflate.Valve with no return function. Halkey Roberts (H-R) Air Valve will fit most inflatable boats , river rafts and RIBs . Halkey-roberts(H-R) valve comes in three parts. One inside part , one outside part and valve cap.