This is a Pulley Unit Set for Various Models. It's from Tamiya for very experienced model builders. FEATURES: Pulley set is designed to attach to a chosen model kit such as a jumping dophin, an elevator, a moving dog, alligator, or revolving bird cage. Contains white, black, and gray plastic parts attached to sprues. Other parts include an electric motor, belt guides, skinny belts, circular pulleys, rivets, a base, and motor holder. Battery operated. Small phillips screws for solid construction. Structure of pulley is kept simple for maintenance purposes like replacing the belt, if needed. Pulley rotates freely, allowing a dog to wag his tail, an alligator to open his mouth, or a dolphin to "jump" into the water, among other chosen motions. Designed for fairly small and simple models. Reverse rotation of pulley is possible. Pictorial instructions included. INCLUDES: One Pulley Unit Set REQUIRES: Assembly Battery Small Phillips Screwdriver Modeling Knife