MEZ-SYPHON-FLANGE system 20 is injected with MEZ-BLUEMASTIC-GEL to provide for the manufacturing of air duct systems with high tightness requirements. By placing the MEZ-BLUEMASTIC-GEL inside the MEZ-SYPHON-FLANGE you are able to meet the requirements of air tightness class C & D according to EN 1507. MEZ-SYPHON-FLANGE has an added lip inside the corner to provide a firm seal against the edge of the duct as well as adding extra rigidity to the structure. Another feature which contributes to the optimal stability of the MEZ-SYPHON-FLANGE is the 45° supporting limb. To meet the high tightness requirements, the inner limb was designed with a slight cant and therefore it functions like a sealing lip.