The baseplate under the foot and heel's is broken side to side and given a gap they fill with foam. The Heelcup is the only thing connecting the two sides of the baseplate. So its a big loop basically. The disc itself is materially hinged, so not a pin hing like Forum Goodvibes but just a section right down the middle of thinner plastic that bends. The problem is that the disc must be mounted perpendicular to the edge. But the flex windows in the heel and toe area aren't big enough to allow for enough flex when the binding itself is set at 15* or more. So if you ride with stance angles at or above 15*, you get very little to no binding flex.
All that said, they are solid bindings and for their category are top tier.