I purchased the DTK-15 standard duct set, but only used one flexible duct, so I'm selling the rest. I opened the box to use it, but the remaining items are unused. - Set contents: 1 flexible duct, 1 straight duct, instruction manual, and a 150φ nipple (which wasn't originally part of the set, but I'm including it since I didn't use it). Thank you for looking.