This is a Universal Gearbox Assembly Kit. It's from Tamiya for very experienced model builders.
FEATURES: Contains a 24T gear, 26T gear, and 8T pinion gear.
Includes small phillips screws, washers, spacers, and rivets.
Other parts include an output shaft, drive case, hexagonal shaft, and worm wheel.
Select one of three speeds according to use: low speed, medium speed, and high speed.
Small motor included.
Direction of output shaft can be altered.
3V battery operated (not included).
Pictorial instructions included.

INCLUDES: One Universal Gearbox
REQUIRES: Assembly
Small Phillips and Flathead Screwdriver
Tweezers
Battery

SPECS: Motor: Length: 1-1/2" (3.6cm)
COMMENTS: Keep out of reach of small children. Contains small parts.
Keep fingers free from moving parts.
Product may overheat during prolonged use.
Instructions and box language written in Japanese and English.