Stair lifts are available for straight or curved flights of stairs and for use indoors or outdoors. Models are available with or without seats. Standard stair lifts are intended for people weighing up to about 300 pounds, and heavy-duty models accommodate larger individuals who weigh 500 to 600 pounds.
Some stair lifts models have seats that fold up or curl around the corner to allow those on foot to traverse the stairs safely. Another feature that allows safe passage for those on foot is a track that folds up to an out-of-the-way position at the foot of the stairs when not in use. Stair lifts run on electricity, with some models using rechargeable batteries that undergo constant recharging via alternating current.