What it does: phosphate filter helps prevent lime and calcium carbonate scale, phosphate sticks to the calcium so it can not stick to surfaces. Heavy Duty Design: made in the USA, reusable blue filter caps(end to end) preserves resin. Reinforced 8" brass crimped hose ext, lead free, internal seal gasket. Superior Technology: filtration applied by sediment pack on inlet and outlet to reduce calcium, dust, rust, sand and silt. No clogging. Simple To Use: plug & play design, no tools required. Fits standard 3/4" garden hose thread. Our proudly made in the USA RS-40W is designed for initial rinse and multi-stage water conditioning. This filter uses a specially formulated phosphate to help prevent lime and calcium carbonate scale. Our filters eliminate the need for large systems with complicated installation, offering a compact, quick and easy solution for initial rinse and multi-stage water filtration. The RS-40W is most effective during prerinse, then soap bucket, rinse bucket, and pre final rinse. Lastly. use our SF-20W filter for the final spot-free rinse.