This Traditional has an innovative design offering two installation options. The perfect choice for those wishing to have either concealed or exposed valve installations and boasts a classic, sophisticated design that offers two installation options. Fully Thermostatically controlled Separate Flow and Temperature Controls Suitable for High and Low Pressure Systems Suitable for either Concealed or Exposed Installations This mixer is compatible with the following plumbing systems: Gravity fed Pumped gravity Unvented systems Mains pressure (Thermal store) Combi Boiler It also has industry standard 150mm Pipe Centres ( Distance Between the Hot and Cold Pipework). If replacing an old exposed unit the diameter of the rear of the valve as above is 75mm. If replacing an old built in unit the diameter of the concealing plate is 195mm.