A manual valve union with two outlets, one connection, and one manual handle is the most common for simultaneous hose routing controlled by the manual handle.
Reverse osmosis is a membrane technology that allows the removal of salinity from water. It is based on a diffusion process through a semi-permeable membrane that facilitates the passage of dissolved gases and low molecular weight molecules without an electrostatic charge.
This type of resin works to remove hardness from water through alkalinity. Cation resin is regenerated very efficiently with an acid, usually hydrochloric.