Features: 1Complete Kit: A complete accessories for smart robot car chassis DIY, with simple mechanical structure, very easy to assemble. 2Excellent 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. 3Battery Compartments: The chassis is equipped with 4 AA battery compartments for the convenience of power supply of the whole system. 4With Switch: At the same time, the chassis is equipped with a switch to facilitate the start and stop of the system, easy to operate. 5Reliable Material: The whole system is highly integrated and made of excellent materials, allowing long term use. Package included: 2 x Car Chassis 4 x Wheels 4 x Motors 1 x For R3 Mainboard 1 x V5.0 Expansion Board 1 x L298N Drive 1 x SG90 Module 1 x SR04 Ultrasonic Module 1 x Obstacle Avoidance Module 1 x Lamp Group Module 1 x USB Cable 1 x Instructions 1 x Battery Box 4 x Bracket Accessories 1 x Module Wiring Row 8 x Connecting Wires 1 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)