This chair has 3 sizes and a Pellicle material that conforms to the user's body and reverts to its original shape when unoccupied. The material is lightweight, breathable and distributes the user's weight evenly over the seat and back of the chair. The chair has 2 height adjustment options. The two stage pneumatic lift provides a wider range of height adjustment than does the single stage adjustment. The chairs Kinemat tilt lets the body naturally pivot at the ankles, knees, and hips. Tilt features include a tilt limiter that allows the user to set the tilt range to limit the amount of recline; seat angle that allows the user to select the tilt range and either a horizontal and a 5 degree forward seat angle. Arm features include a fully adjustable option that moves the arms 4" vertically and pivots the armpads 15 degrees outward and 17.5 degrees inward. The work chair meet CAL133 and Boston Fire Code requirements. This lumbar pad fits into the back of an Aeron chair to further support the lower back. The pad can be reversed to adjust for more or less support. The arms are available in a fixed position, height adjustable, or fully adjustable features. The chair frame can be ordered in mica or graphite with ten different pellicle colors to choose from The 'B' size chair fits people with height being between 4' 10" to 5' 2" with weights varying from 140 to 270 lbs, and heights of 5' 3" to 5' 9" with weights of 140 to 250 lbs, heights of 5' 10" to 6' 2" with weights between 90 to 230 lbs, and heights of 6' 3" to 6' 6" with weights between 90 to 170 lbs.