White-Rodgers 21M51U-843 universal two stage hot surface ignition control

W-R 21M51U-843 universal two stage hot surface ignition control, 3 speed circulator furnace control kit; replaces 50M51-242 and all 50M61 two stage hot surface ignition systems with 80v or 120v ignitors, also replaces Armstrong R43207-001, R43207001, 43207001 and 43207-001