Suttner ST-64 Upstream Chemical Injector 4.0 - 7.0 GPM with 1/2" NPT. If you like the way soap is applied at self serve car washes, this accessory is for you

Features:
• Designed to introduce detergents into the water system upstream from the pump at high pressure
• The "on-off" plunger is then used to control the injection
• Easily connects to inlet of pump at garden hose connection
• Adjustable chemical flow
• Chemical strainer and 4’ PVC tubing included
• Choose size based on flow rate of your pressure washer

See the ST-64 in action on YouTube

Specifications:
• Size: 4.0 to 7.0 GPM flow rate
• Max Temperature: 140° F
• Inlet: 1/2" Female NPT
• Outlet: 1/2" Male NPT
• Optional ST-61 chemical metering valve adjusts from off to full flow
• Weight: 0.80 lb