chair lift for stairs

A stair lifts is a motorized seat that runs up and down a staircase on a track / rail.
Stair lifts come in three main variants:
The most common seated models, Perching / standing models and models with a wheelchair platform.
Stair lifts are available for both curved and straight staircases, straight stair lifts are cheaper than curved ones.
Stair lifts are also known as ‘stair elevators’, ‘inclinators’ ‘stair chairs’, ‘staircase lifts’ and ‘stairway lifts’.