Harvia Electric Contactor FX-503 can be used with all Club model 208V 3Ph heaters. Relay is required for heaters 8 KW and over when F-2T or F-2 wall control is used. Made in USA, this electric contactor box has a superior quality construction and is highly efficient. This unit includes the box only and does not include the heater or controls. All FX Contactor Boxes are 6"w x 8"h x 4"d.