Aluminum is an armchair designed by Mats Theselius in 1990 and produced by Källemo. The armchair, as the name suggests, is made of aluminum and is available in either a polished or matte-lacquered finish. The seat is upholstered in Tisnsjö Garveri core leather and can be chosen in several colors. The back is upholstered in cold cured foam while the seat in cold cured foam and Dymetrol. The chair frame can be matched to suit the upholstery and is available in natural beech, black, or walnut glazed beech.

Aluminum is part of a series of products that many call Theselius armchairs, where the common feature is the use of large pieces of metal combined with leather. This combination makes the armchair as elegant as it is industrial in its look. Theselius chairs are now highly sought after around the world.