A great introduction to the pulley, the Pulley Unit Set is similar in function to a gear box. 
Five pulleys in all are included in the set along with a universal arm and pulley mounts. A motor and motor mount box are also included. Combine this set with other Tamiya Construction and Robotics products and let your imagination run wild.
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.
REQUIREMENTS:
- Battery
- Small Phillips Screwdriver
- Modeling Knife
- Sprue Cutters
- Long Nose Pliers
SPECIFICATIONS:
Base: Length: 4-3/4" (12.3cm)
Width: from 1/2" to 1" (1.5cm to 2.5cm)
Height: 1/4" (7mm)
COMMENTS: 
- Due to small parts that could cause a choking hazard please keep away from children 3 years of age and younger. 
- Instructions and box language written in Japanese and English.
Used with permission, copyright 2014 Tamiya America & Hobbico, Inc.
Copyright 2014 Brey Corp. t/a Hobby Works.