SainSmart 4WD Drive Aluminum Mobile Robot Platform for Robot Arduino UNO MEGA2560 R3 DuemilanoveSilver Can hold many controllers, drivers, sensors and RF modules etc. Supports plate with controller mounting holes, 2 dof pan. Tilt holds down groove, collision switch mounting hole, can be added with sensors. Elastic rubber tires. Damping, gripping, and wear-resisting. Light weight, high strength and no deformation characteristics.