Two different Hypro Injector Heads: Model 3396-0006 for Hypro Series 5321 and 5324 Piston Pumps Model 3396-0014 for Hypro Series 5300 Cast Iron Piston Pumps ie. 5315, 5320, and 5330 Please choose the injector to match which Hypro 5300 Series Pump you have. Specifications: Cylinder head: Cast iron with special flow Inlet Port: 1/8" NPT (F) can be positioned to face any direction Brass Valve Stem: Needle type metering, for accurate mixing of injected solution Control Knob: Calibrated with 9 steps in a 360 degree turn Max. Fluid Temperature: 140 degrees Fahrenheit Hypro Series 3396 Liquid Injector Head mounts directly on the pump, replacing the regular cylinder head. It feeds solution directly into the pump, mixing it with the regular pump flow. No internal pump parts are removed to install the injector. This allows the injection of soap, detergents and other solutions. Injector heads are often found on pressure washers that have a Hypro piston pump, or other cleaning machines. **You must have a Hypro 5300 Series Pump for this to work. It cannot be used on any other pumps.