Swivel chairs may have wheels on the base allowing the user to move the chair around their work area without getting up. This type is common in modern offices and are often also referred to as office chairs. Office swivel chairs, like computer chairs, usually incorporate a gas lift to adjust the height of the seat, but not usually large swivelling armchairs. A draughtsman's chair is a swivel chair without wheels that is usually taller than an 'office chair' for use in front of a drawing board. They also have a foot-ring to support the legs when it is not possible to reach the ground.