How does it work?

Specially machined clamps attach to the seat frame. For Catrikes that don't fold, they go on the straight part under the seat between the main tube and where it bends up. On Catrikes that fold, a different set of clamps go on back of the seat near where the seat angle adjusts. A support tube comes out sideways and over to where the accessory mounting tube needs to be. The end of the support tube has a T clamp that holds the horizontal accessory mounting tube beside the seat. The accessory mounting tube is long enough to hold whatever you'd like.