up and folds out with the folding and unfolding of the apparatus the seat assembly includes a substantially rectangular flat seating member 54 supported on a pair of parallel disposed pivotally mounted support bars or rods 56 which are pivotally secured by means of detachable pins 58 to brackets 60 the brackets 60 include a plurality of pin receiving holes 62 positioned at the various levels vertically with respect to the floor to permit vertical adjustment of the seat the pins 58 are preferably of the frictional ball retainer type such that they merely need be pulled out and pushed back in and are retained in their position by frictional balls a pair of adjustable legs or struts 64 are pivoted at their upper ends to brackets 66 secured either to seat 54 or to the support rods or bars 56 the adjustable legs 64 are also pivotally connected to the lower end by bracket means 68 to the front panel 10 as best seen in fig1 the legs comprise outer and inner telescoping members 64 and 65 and having a plurality of transverse holes 70 in which are disposed a frictional pull pin 72 for adjusting the length of the leg to correspond to the proper elevation of the seat member 54 this.