30mm X 26mm    Fins spacing   Min. - 1.6mm   Max. - 4.2mm   zoom geometry Constructive specifications   Copper tube                        Ø 12mm                                                Ø 9.52mm (3/8") Smooth-grooved Fin Aluminium Prepainted aluminium Hydrophilic aluminium Copper Frame Galvanized steel Smooth / goffred / prepainted aluminium Peraluman Brass Stainless steel