Alemite 1608-B Drive Fitting, For Low or Medium Pressures, For 5/16" Drill, 35/64" OAL Drive-in grease fitting with straight head and barbed end for avoiding tapping of line Nickel-copper alloy and zinc-plated for resistance to corrosion Ball check valve for keeping out contaminants 1/4" length, 5/16" diameter serrated shank for secure seal