The Simpson 4500 PSI is for cold water machines and is designed to replace or upgrade your existing pressure washer spray gun. This spray gun is equipped with a trigger safety lock-out and can be used with pressure washers with standard threaded high pressure hose and wand connections. The 80148 has an ergonomic design and easy pull trigger helps reduce hand fatigue for all day use. This gun is designed to fit most gas pressure washers and is rated up to 4500 PSI.