A 6-wheeled (with retractable wheels) undercarriage for a school backpack is sold for 30 manat. Type: 6-wheeled special mechanism (for easy climbing and descending stairs). Condition: In good/working condition, no problem with the mechanism. Color: Pink (suitable for girls). Height: The height of the handle is adjustable and foldable. It takes the weight of the backpack off the child's shoulders, making it very convenient to use.