Chapotraphouse

It's a plastic tube because it is a prototype ie a demo. He made it from pvc plumbing pipe. It is meant to demonstrate a concept. The real product would be made from a stronger material. He's probably trying to acquire funding from investors at the convention.

I would guess that an anchor brake would be more viable on a surface where the wheels don't have traction. Wet grass as example would be slippery for wheels, but an anchor would hold the wheelchair in place.