Zehnder ComfoTube Flat 51, Cross Piece 188633 it has a superior internal it has a superior internal mechanism which ensures smooth operation and has an impact resistant TPR covered ABS casing Ergonomic TPR (Thermoplastic Rubber) handles for a comfortable The cross piece comes complete with award winning RapidLock® connections to quickly form an air tight and robust seal by simply push fitting the semi rigid ductwork when combined with the o ring seals sold separately It measures 67mm high x 342mm wide x 342mm deep The compact cross piece can be used to cross over two lengths of Zehnder ComfoTube Flat 51 in a height restricted space