WE-S447 accommodates the way many of us sit throughout the day, ?perched” mid-way on the seat. This position is popular but leaves the lower spine unsupported, causing back fatigue and discomfort. WE-S447 offers a ratchet-back mechanism that gives you the choice of a normal back position for sitting fully on the seat or the far forward position for sitting midway on the chair. With WE-S447, the chair does the work ? not your back.