Tank chassis: 
This is a professional HQ chassis, High torque motors with Encoders,
  Product configuration: The tank chassis is made of all-metal, solid and stable, four strong powerul motors with Enoder builtin, can be forward and backward, turn left turn right, turn around and other functions, running Smooth, smooth and unimpeded, very good ground friction crawler due rubber treads, can run on the non-smooth surface can easily cope with, and the entire chassis platform broad and smooth, for customers to install Electronics circuits PCB battery this chassis provide enough space. The chassis platform can be fitted with a robot arm

Load chassis , large friction track

Product parameters:
  Chassis size: 236mm x 166mm x 60mm (L x W x H), due to different batches, the size may have small change.

  Motor operating voltage: 9 to 18V. Green line, motor positive pole.
Yellow line, motor negative.
Blue brown white, are encoder wires.
no-load current of single motor is about 300mA, RPM 7650 per minute on 12V, since Ratio is 90:1  after deceleration the output RPM 85 per minute, load weight 10kg  to 12KG