Specification： 24mm shaft Spare parts (seals, valves and plungers) are available These pumps ship with no oil . Please remember to fill with oil before use (as per included instructions). The oil should be changed after the first 10hrs of use (break in period) and then after every 100hrs 24mm Solid Shaft Pressure Power Washer Pump 3600 PSI 4.9GPM Belt Drive Replacement Mi-T-M 3-0308 Feature： Will Replace General pump TS series. AR Rk sries .Does not ship with frame Rails, Using existing frame rails may need modification Unloader Valve Included, Can be used with Universal external bypass unloaders as well. .