Kair Ducting Reducer 125mm to 100mm - 5 to 4 inch125mm / 5 inch Side125mm female spigot will fill fit over male fittings (Such as bends, connectors, etc). Rigid round 125mm ducting pipe Part: DUCVKC267 will require a male connector / coupling Part: DUCVKC355. 127mm Flexible ducting Part: DUCP0092/127/35 will fit over and require tape or metal hose clips Part: DUCVKC611 to attach. For permanent fixings, seal joins with silicone sealant or tape. 100mm / 4 inch Side100mm Male Spigot will fit into 100mm straight ducting Part: DUCVKC250. Can be used with rigid plastic ducting systems. Can be used with flexible ducting systems with use of metal hose clips (Part: DUCVKC264. For permanent fixings, seal joins with silicone sealant or tape. Max / Min Temperature: +60c / -15c.Kair plastic rigid ducting is perfect for DIY and trade use. Perfectly suited for ducting your Tumble Dryer, Bathroom or Kitchen extractor fan, Hydroponics, In-Line Extract Fans, or Cooker Hood. This reducer can be used as a part of a long ductwork run for a variety of purposes including whole house ventilation, passive stack vent, positive input, air conditioning, HVAC, and Heat Recovery Systems.