ITEM NAME:2WD Motor Smart Robot Car Chassis Kit Speed Encoder Battery Box for Arduino W4R2 2WD Motor Smart Robot Car Chassis Kit Speed Encoder Battery Box for Arduino W4R2 100% brand new and high quality. Mechanical structure is simple, it is easy to install. This car is the tachometer encoder. With a 4 AA battery box and power switch. (Batteries not included.) Can be used for distance measurement, velocity.Can use with other devices to realize function of tracing, obstacle avoidance, distance testing, speed testing, wireless remote control. colour: Transparent Material: plastic Gear Motor reduction radio: 1: 48. Size: 22 x 12 cm(L x W); Wheel Size: 6.5cm (Dia.) x 2.7cm (H) Package Includes: 1 x Car Chassis 2 x Gear Motor(1: 48) 2 x Car Tire 2 x Speed Encoder 2 x Fastener 1 x Universal Wheel 1 x Battery Box (battery is NOT included) All Necessary Screw And Nut Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm..2 x Speed Encoder. colour: Transparent. With a 4 AA battery box and power switch. (Batteries not included.). 1 x Car Chassis. Gear Motor reduction radio: 1: 48. 1 x Battery Box (battery is NOT included).