: L*W*D (12.6X19.3X7.1 inches ) please note with 6 wheels can climb stairs Trolley backpack can help student reduce load and contribute for the children healthy growth Good quality of Nylon,tear resistant and water resistant.Designed breathable back and shoulder Strap are made of ventilate material. Equipped with 6 durable mold wheels ,which can make it easy to adapt to a variety of terrain. Ergonomic decompression breathable strap design, effectively avoid the burden on the child's shoulder bag, for your child's healthy growth escort.