Stable mixed temperature performance with durable construction for long life. Due to the unique mixing chamber design, Caleffi MixCal™ produces very stable mixed water temperature as inlet temperatures and pressures vary. Scale formation is minimized via sliding surfaces constructed of an anti-scale polymer, thus guarding against seizing or erratic mixed temperatures. O-ring seals made from durable peroxide-cured EPDM resist wear from common water treatment additives such as chlorine and chloramines.