Back to Back installation instructions Your shower valve is equipped with a reversible cartridge, suitable for back to back installation, a reversible cartridge will allow you to modify the direction of the water supply to the comment orientation without changing the pipe locations, as in the case of back to back bathrooms. Remove the handle and cap (1) Carefully remove the “E” clip from the body with pliers. Remove the stem ring from the cartridge body with pliers. Tum valve stem a full 180°.