A panel having particular utility in a chair or other apparatus for receiving an occupant in a seated position includes an envelope of resilient material having an opening with a fastener for closing the envelope. An envelope support frame is substantially rigid and formed in a closed loop. The envelope support frame is positioned inside the envelope to tension the resilient material of the envelope in one or more tension zones. A fastener is closed to envelop the envelope support frame with the resilient material. The width of each tension zone when the envelope is in a its relaxed state is different than the width of each immediately adjacent tension zone.
