Makro Teknik flange profiles are produced to ensure maximum strength, tightness and mountability for air ducts. Sealing, non-leaking, frost-proof Butly mastic is applied on duct settlement joints along the flange. Alternative connection profiles in DW 142 and SMACNA standards are given which could be used in duct systems. With its definitions and approaches, SMACNA underlines especially the savings of the use of new technology. Duct flange defined as one of the alternative connection elements, provides saving in time and labour as well as maximum sealing and rigidity when applied correctly. When necessary accessories are used, it increases mounting ability, also gives the system an aesthetic integrity.