The seat surface should be the correct size for the individual. It should have the forward edge turned down and be firm, flat or contoured to meet individual desires. A flat seat allows for the easy movement in chairs during the day, and assists in upright posture. The seat tilts forward or rocks back to accommodate different work tasks. Sitting in a forward tilted chair will assist in upright position of the spine and head.
Castors allow for easy movement between work surfaces.
They come in various types to match floor surfaces. Arm Rests are generally preferred to give support to arms and assist with good sitting posture. They should be adjustable to meet individual needs and adjust to desk height. Back Rest must have a well formed lumbar pad to support the lumbar spine, be height adjustable, have an adjustable inclination and lock at any desired position. Models with hydraulic lifts are common.