This is a platform fixed along the handrail of the stairs. It moves parallel to the stairs. The width of the stairs for such a device should be from 2 m, the height of the doorway — from 2 m. It is used both inside the building and on the porch. They differ in the length of the path — to advance one stairway or the entire staircase. For safety, they are equipped with an emergency stop button, an anti-vibration, anti-jamming and anti-jamming device.