Caster Wheel on swivel plate for Robots, Smart car, Platform Trolley, Trolley Cart, and other moving things. The wheel is mounted off-center on the swivel plate and will always line up in the direction it’s moving. In case of installation in robotics projects or DIY projects, the spacing hole has a size of 30 x 23mm. The biggest advantage of using these caster wheels is to reduce resistance and avoid wear and tear. The universal swivel caster wheel is designed with a hole diameter of 4mm. The wheels used in the swivel caster wheel have a diameter of 21mm and a width of 4mm. Dimensions (wheel): ø 25.4 x 12.7mm; Max. load: 10kg; Material : Nylon, Metal Dimensions (plate): 38 x 32 x 1.3mm; Height (total): 35mm Mounting holes: ø 4.2mm; Centre Distance 29 x 23mm