Patent ID: 8870294

Claim:
A chair comprising: a collapsible frame comprising two chair sidepieces, each sidepiece having an internal face and an external face, each sidepiece comprising: a base portion comprising an upward facing edge for contacting a portion of a profile of a seating ball, the base portion further comprising a frontal aspect, a back portion comprising a back edge and a hole in its upper region, and one or more hinge attachment sites positioned to connect the two sidepieces at their respective back edges, the sidepieces, when connected by hinges at the one or more attachment sites, being moveable between a collapsed arrangement and an open arrangement; and a cross member comprising an upward facing edge complementary to a portion of the profile of the seating ball, the cross member configured to mate with the frontal aspects of the two sidepieces, such mating stabilizing the two sidepieces in the open position, wherein when the frame is in an open arrangement and when the cross member is in place and mated with the frontal aspects of the sidepieces, the upward facing edges of the two sidepieces and the cross bar collectively form a three-strut seating ball cradle to accommodate the seating ball, and the holes in the upper region of each sidepiece collectively form a lumbar support ball nesting site.