It uses the floor horizontal as a sheer plane. It's a decent way to involve a much large structure. It's a bunch of work and a PIA to do it.
I tend use 2x2 or 2x3 tube that is .080-.120 thick. Worked well for years and if you are putting in a bar/cage, tie a bar into the connector or make an outrigger to the rocker to land the main hoop.