Required for Outboard and Jetski engine flushes, and most Inboard flushes. Constructed with a 3-position control valve Off, Rinse, Salt Attack. TO FLUSH ENGINE: put 40-60mls (min 1/2-3/4 cup) Salt-Away concentrate in cup for up to 90hp motor, and for 90-300hp use 80mls (full cup) to flush your engine, wash boat, trailer, fishing and diving gear. Follow engine flush instructions included or visit web site. The receptacle holds 100ml and has been tested to withstand water pressure up to 120 psi. Ideal for outboard flushing with our Deluxe Muffs and wash down by adding our spray gun. The Salt Attack spray gun also works great with Marine Washcoat and Shine!