1.5 inch 38mm Plastic omni wheel is the smallest omni directional wheel 14184 features:

The (1.5 inch) 38mm Plastic omni wheel is the smallest omni-directional wheel in all omni wheels. It is unique as they are able to roll freely in two directions. 

And this 38mm omni wheel has 8 PU rollers. Its rollers are more durable, robust and flexible to provide the wheel 360 degree movement easily. This 38mm omni wheel 

apply to the small robot cars , robot platforms, small toys .

Specifications:

Diameter: 38mm

Width: 23.4mm

Axial width: 4mm

Number of plate: 2

Number of roller: 8

Body material:plastic

Roller material: TPR

Net weight: 20g

Load capacity: 2 kg

Compatible Hubs:

3MM   18036

4MM   18037

1.5 inch 38mm Plastic omni wheel is the smallest omni directional wheel 14184pictures as below:

What are the advantages and disadvantages of the Omni wheel?

The advantages of the Mecanum wheel and the omnidirectional wheel are flexibility and convenience, and the disadvantage is expensive. The omnidirectional wheel, as the name suggests,

 can move in any direction, at any angle, and in any direction. mecanum wheel these rollers having an axis of rotation at 45° to the plane parallel to the axis of rotation of the wheel.