The Spiral round Flange profile is as an integral part of round duct connector system, it is roll-formed from Hi-Tensile GI steel. With the closure band is engineered to simplify the connection process, widely adopted in Building construction Industry – commercial and residential. Two sizes flanges 20mm & 30mm are suitable for difference diameter pipes connection. Pls feel free to contact with us for further details!Customized machine is welcome! MAIL: JV@JACK-AIVA.COM / WHATSAPP: +86 139 15206868