Tap Extension, Overall Length 5 1/8 in, High Speed Steel, For Tap Square Size 0.2380 in, Fits Tap Size 5/16 in, For Tap Shank Dia. 0.3180 in, Shank Dia. 5/16 in, Includes Nut, Body Dia. 1/2 in, Coolant Fed Coolant Through, Extension Square Size 0.2380 in