NOS 3-PC Mr. Heater Ignition Module Flame Control Control Board SK-07 Heatstar
Based on internet research of the model numbers, I believe this fits both Mr. Heater and and Heatstar models MH50KT, MH75KT, MH125KT, MH175KT, MH210KT, HS50KT, HS75KT, HS125KT, HS175KT and finally HS210KT.