This flue brush is designed to clean flue tubes in Clean Burn models CB 85 C/D, 86 AH/BH, 90 AH/BH/C/D, 1800, 2800, 4000 PLEASE MAKE SURE YOU ORDER THE APPROPRIATE HANDLE FOR YOUR BRUSH. Your tubes should measure 3 1/2" on your furnace. Clean Burn part # 70002. Please check out our 3' and 4' handles too!