Tony,
Most of the support comes from the assembly that sits below the Aeration Bench. These two pieces are bolted together using four 1/4"x20 machine screws and washers. It forms a pretty rigid structure in this configuration. The four corners, and the handle areas are especially strong when you sit the Aeration Bench on them.
The two bolts in the upper Aeration bench do provide support, but only in a secondary capacity.
Raybo
