Equal T piece male spigot will fit into round 100mm ventilation pipe or 102mm flexble ducting. Can be used to duct in to different areas and join different duct runs together. Round rigid ducting provides superior airflow performance vs. comparative size rectangular or flexible duct. Easy to install and durable, just push-fit duct and fittings together. Compatible 100mm Round and 110mm x 54mm Rectangular fittings, outlets, and grilles., Weight: 0.26 pounds, Manufacturer: Kair