Kair Ducting Adaptor 110mm x 54mm to 100mm - 4 inch Rectangular to Round Straight Channel Connector - Female RECTANGULAR 110mm x 54mm The flat end is a female spigot and fits over 110mm x 54mm Rectangular Duct Pipe Part: DUCVKC249. ROUND 100mm / 4 inch Circular end is a 100mm round female spigot that will accept any male 100mm round fittings. Allows you to convert between round and rectangular ducting systems. Made in the UK using high-quality Polystyrene/Polypropylene plastic. Max / Min Temperature: +60c / -15c. Easy to install and durable, just push-fit duct and fittings together. For permanent fixings, seal joints with silicone sealant or tape. Airflow performance independently tested by BSRIA or BRE. Suitable to use in compliance with Part F Building Regulations. Static Pressure Drop in Pascals: 15 l/s = 4.80 Pa - 30 l/s = 20.40 Pa - 60 l/s = 86.20 Pa. Perfectly suited for ducting your Bathroom or Kitchen extractor fan, hydroponics, in-line extract Fans, tumble dryer, or cooker hood. This item 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 ventilation, air conditioning, HVAC, and Heat Recovery systems. Kair plastic rigid ducting is perfect for DIY and Trade use and provides superior airflow performance and durability versus flexible duct.