ANSI Flange Flex Connector
Because these are designed for connecting sections of pipe, ANSI Flanges are much wider than the one- or two-inch angle flanges typical to industrial ductwork. This means that flexible connectors for most pressure blowers will need custom-fabricated flanges.
Custom frames do cost more than those made of rolled angle, but knowing this ahead of time will avoid a pricing crunch later on.
BAM also makes flexible connectors with frames to match JIS, the Japanese Industrial Standard.