Motorise your KNEX models to make them more realistic with these two battery-powered motors. (AA; batteries not included). Turn concept models into Technology at Work. This set contains 2 battery operated motors. Build, investigate, and experiment with motorised models that have constant speeds and continuous operation. Build two models of the same device with different gearing systems and operate them side-by-side to observe the effects of the gearing variations. Compatible with all classic KNEX models from cosmic quest and cars building set to 52 and 70 model building set; Recommended for builders age 5+. One supplied. Size H8.26, W13.97, D15.88cm. Batteries required: 4 x AA (not included) plus . For ages 5 years and over. WARNING(S): Not suitable for children under 3 years old. Only for domestic use.