DUO Omni Wheels are compatible with the REV DUO System and have rollers mounted around the outside which passively rotate at 90 degrees to the powered direction of the wheel. DUO Omni Wheels can be used to make it easier to turn with skid steer robots or can be used to make more advanced robot drive trains like kiwi drive. DUO Omni Wheels can be double stacked to create a continuous outside roller surface.