Vermiculite: Grade 4 Uline S-3393, 4 Ft3 - 3170-205 Hearthstone MSRP: $10.65 Vermiculite: Grade 4 Uline S-3393, 4 Ft3 for Hearthstone heating units.Genuine OEM partMay fit other models, please check your owner's manual for part number compatibility.
