Atrio® thermostatic mixers ensure the temperature you select remains constant for the duration of your shower. No shocks, no surprises, just a constant stream of perfectly mixed water at the temperature of your choosing. GROHE Central Thermostatic Mixer, Atrio® Collection, 1 Handles, Cross Handle, 7-3/8 in Dia Trim, Thermostatic Ceramic Cartridge, Hand Shower: No, Wall Mounting, For Use With: GrohTherm 34 397 or 34 331 Rough-In Valve, Brass, Polished Chrome, Import