The seat design should take into account the distribution of weight. And can be easily handled in a sitting chair should be adjustable in both height and tilt. A good chair must make the ride. Sitting in the correct manner. Weight should fall hips or buttocks Not the fall of the femur The height of the chair should not be as high as the distance between the surface of the femur. Because thigh tissue can not tolerate pressure like tissue rump or bottom. The chair is designed to sit too low to cause the angle between the torso and thighs of quirk. This may cause pain in the stomach. The chair is too high, the pressure will fall thigh area. It femur senselessly And if the ride will be resolved by moving the hips forward, leaning back, which is not comfortable sitting position. As a result of spinal flexion arc. Backrests have to look at the underpinnings below are fixed. The area is suitable for the type of chair with a mechanism to rotate the armrest can be adjusted to the height of the elbow. When the forearm and upper arm hanging in a position 90 degrees with the forearm arm movement should not interfere in the work.