What's in the box:

4pcs 65mm Mecanum Wheel Omnidirectional Wheel 2.5-inch Omni Wheels Universal Wheel Smart Car Robot Accessories (Standard)

65mm engineering plastic mecanum wheels include 2 right wheels and 2 left wheels. Each wheel consists of 9 rollers and can be driven independently. These wheels can be moved in any direction without changing the direction of rotation of the wheels. Each of the four wheels contains a series of rollers whose axis of rotation makes a 45 angle to the plane of the wheel.

Features:
Ominidirectional Wheel: 4pcs omni wheels is able to move straight ahead, turn round, turn of rear axis, etc. By changing the direction of each wheel, the robot cart can be moved and rotated in any direction.
Compact Construction: made of high strength environmental friendly materials with smooth surface to assure the movement agility of wheels.
TT Motor Coupling Included: equipped with 4pcs couplings for connecting with TT motor.
Good Quality: processing by precision molds, thus the wheels are not easy to damage and sturdy enough for load the toy bricks.
Applications: apply for mounting on intelligent robotic car, compatible with Arduino Raspberry Pi DIY project.

Specifications:
Material: ABS
Quantity: 4pcs
Item Size: 65 * 30mm / 2.56 * 1.18in
Item Weight: 240g / 8.47oz
Package Weight: 280g / 9.90oz
Package Size: 20.5 * 14.3 * 4.2cm / 8.07 * 5.63 * 1.65in

Packing List:
4 * Wheel
4 * Coupling
4 * Screw
1 * Mini Wrench