Feature: 1. Complete Kit: A complete accessories for smart robot car chassis DIY, with simple mechanical structure, very easy to assemble. 2. Excellent Components: Equipped with a 20 wire tachometer code and a photoelectric gun to quickly form a gun system. Can be composed of speed, distance and closed cycle system. 3. Battery Compartments: The chassis is equipped with 4 AA battery compartments for the convenience of power supply of the whole system. 4. With Switch: At the same time, the chassis is equipped with a switch to facilitate the start and stop of the system, easy to operate. 5. Reliable Material: The whole system is highly integrated and made of excellent materials, allowing long term use. Specification: Item Type: Smart Robot Car Chassis Kit Material: PCB Power Supply: 4 x AA battery (not included). Package List: 2 x Car Chassis4 x Wheels4 x Motors1 x For R3 Mainboard1 x V5.0 Expansion Board1 x L298N Drive1 x SG90 Module1 x SR04 Ultrasonic Module1 x Obstacle Avoidance Module1 x Lamp Group Module1 x USB Cable1 x Instructions1 x Battery Box4 x Bracket Accessories1 x Module Wiring Row8 x Connecting Wires1 x 1 Screw Pack (4 x Long Screws, 4 x Medium Flat Screws, 5 x Medium Pointed Screws, 7 x Short Screws, 6 x Nuts)1 x 2 Screw Pack (3 x Accessory Brackets, 2 x Medium Screws, 1 x Short Screws)1 x 3 Screw Pack (8 x Long Accessories, 4 x Round Accessories, 8 x Long Screws, 8 x Short Screws, 8 x Nuts, 4 x Long Bolts)