This replacement is the combustion blower gasket that will fit on many of the pellet stove models but may also fit a variety of other models and manufactures based on size and shape

Commonly fits on the following models:
Drolet: Eco-45
Osburn: Hybrid-45
Enerzone: Bio 45MF
Flame Energy: FP-45 

Measurements: Outer - 5" x 4 1/2", Inner - 3 5/8" x 3 1/8"