The F221887 Filter Kit fits the following heaters (and others):
Mr. Heater- MH50KTR, MH75KTR, MH125KTR, MH175KTR, H210KTR
Heatstar- HS50KT, HS75KT, HS125KT, HS175KT
Mr. Heater Contractor Series-TS75KR, TS125KR, TS175KTR,TS210KTR
Mr. Heater Contractor Plus- PA50KR, PA75KTR, PA175KTR, PA210K
DeWalt- DXH50K, DXH75K, DXH135K, DXH185K
