Abstract: A seat frame for mounting on a chair frame for supporting a seat pad and seat back. The frame is formed by a pair of spaced apart side rails, each rail having a plurality of spaced apart parallel transverse mounting beams extending therefrom towards the opposite rail. A central beam is telescopingly and releasably engaged between each corresponding mounting beam on the rails. Chair frame mounting fittings and seat back mounting fittings are releasably secured to the side rails.

Abstract: A detent for releasably securing an inner telescoping tube within an outer telescoping tube. The said tubes having alignable openings in the walls thereof for receiving the detent. The detent is formed by a detent pin which extends through the tube wall openings and releasably latches the tubes together. A leaf spring secured at the inserted end of said inserted tube extends within the outer tube into supporting and biasing engagement with the detent pin. The spring biases said pin into the latching position. For releasing the detent, a bell crank is pivotally mounted within the inserted tube. One end of the bell crank is engaged with the locking pin and biasing spring and the other end is secured to an actuating knob which extends through the wall of the inserted tube.