seat portion and the base 78 shown here with casters fig3 is a view of the underseat tilt holding block mechanism 85 and finger operated handle 82 which when activated will maintain the office chair in a 10 u00b0 tilted angle when the chair seat is physically held in a tipped up position the hold block 85 is released from its holding clip 83 the hold block is then slid in a rearward direction until it wedges under the adjusting handle 86 contacting the adjusting handle post 87 holding the chair seat at the selected tilt angle fig3 shows the flexor leg 73 75 in a swung down position from its stowed position on pin 92 the flexor leg is held in position by pin 91 rigidly connecting it to the lower chair arm 90 where it can be propelled by the use of the bearing hinge 72 in an oscillating arc forward and back leg foot movement with pressure regulated by the pneumatic shock absorber 74 a two way resistant pneumatic cylinder and piston the lower flexor leg inner tube 75 being held in position by spring 88 secured to both outer tube and inner tube with pins thus allowing for difference in leg length during operations with the foot strip padded roll 80 and under foot.