US Patent Widened Base Wing Concave Shaped – Aiming at the existing wing convex shape design cushion on the market which is unstable and can’t stay in one-spot, we have Improved the larger and more stable cushion base accordingly. After compression tested, it can withstand a max load of 650 LBS. The unique ergonomics ultra-wide convex shape seat cushion can perfectly fit your round convex hips and relief the pain of “sit bones” (Patent No. 29790220)