In a nutshell:
These bags are specifically made for the Catrike Expedition, Road and Speed. They are made right here Sherbrooke, QC, Canada from 600 denier polyester fabric with foam and high density polyethelene stiffeners. They are sold as sets and fit snuggly on each trike. No rack necessary! The designs are made to carry from the frame and require absolutely no other hardware.
Important Note: This bag will not fit some of the newer models with the adjustable seat.