EzyRoller works like this, using a locomotion principle called cambering motion. The simple left/right movement made by your legs pushing on the moving front bar creates an action/reaction similar to one used by snakes. There are no chains, no batteries just kid-generated power. The steel frame and polyurethane wheels ensure a solid and smooth ride on most surfaces (except grass and sand). With its snake-like motion and extendable steel frame, the award winning Ezyroller is HOURS of fun and laughter for kids aged 4 to 14. It’s a super smooth, super cool ride! Up to 150 lbs. 20'L x 16'W x 12'H. Made of steel and plastic. Do not ride on sloped surfaces, near roads, cars, pools or when visibility is impaired. Always use protective equipment; always read safety instructions before use.