This Heater Relay Board Retrofits Into Iq-2020 And Advent Controls. Replacement Option For: Mfg # 74618 Mfg # 73355 Mfg # 73357 Mfg # 74556 77119 Watkins Circuit Boards Printed Circuit Boards (Pcb) Specifications Category: Circuit Boards Subcategory: Printed Circuit Boards (Pcb)