Patent ID: 8591388

Claim:
An exercise device comprising: a top surface opposite a bottom surface; a first end opposite a second end, said first end substantially parallel to said second end in at least one plane to enhance stability in a second configuration; a first side opposite a second side; a single convex dome on said bottom surface, such that said single convex dome is configured to provide instability in all directions when said single convex dome contacting a support surface; an arched ridge on said top surface for supporting directly thereon a portion of an exerciser's body in at least one exercise configuration, said ridge extending from said first side to said second side, said arched ridge having an arch curvature that is substantially constant along a length of said arched ridge; a first trough formed between said arched ridge and said first end; and a second trough formed between said arched ridge and said second end; in a first configuration said exercise device configured to provide an unstable exercise platform when said bottom surface is positioned downward with said convex dome contacting said support surface; in said second configuration said exercise device configured to provide a stable exercise platform when said top surface is positioned downward with both said first end and said second end contacting said support surface.