1. Inner check valve: the check valve inside the valve body is to insure the hydraulic oil will not be returned. 2. Inner relief valve: the relief valve inside the valve body is able to adjust the hydraulic system working pressure. 3. Oil way: parallel circuit, with power beyond. 4. Control way: manual, air, air&electric, micro-switch, electric&hydraulic control. 5.Valve construction: monoblock construction, 1-8 levers are available to assembled as you requests. 6.Spool function: o, a, y , p etc. 7. Flow 40 l/min with pressure 160bar, 200bar, 315bar 8.Spool returning type with t (spring return) and w (ball locking) 9. Joining port: l (screw connection) 10 .Nominal diameter: g1/2; g3/8; m18*1.5