Coupling head size : 1/2 BSP,M18*1.5,M22*1.5, 1/2 BSP Coupling head / trailer brake coupling / Glad Hand 1)Material : cast iron, aluminium2)It is with black rubber seal in it. to reinforce the safety of the air brake system. it is easy to use and fix.3)use to connect the air brake system of the heavy truck, semi-trailer, full trailer, tractor and so on.4)Available Size : M22*1.5, M16*1.5, 1/2 BSP ...