MIFAB® Series MI-FLEX-AH (specify size) of flexible rubber couplings are manufactured from neoprene compound that meets the requirements of ASTM C564 and stainless steel clamps tightened with 5/16” Type 300 stainless steel hex head screws. MI-FLEX Series of flexible couplings are tested and certified to ASTM Standard C1173 and CSA Standard B602 and listed with IAPMO.