Mini V-Wheels are the more compact alternative to the standard V-Wheels. Like the V-Wheels, these too are constructed of high-density acetal plastic for low rolling resistance and excellent wear characteristics. The Minis however are turned down to a smaller size to create more compact linear motion assemblies - and with fewer parts. Whereas the Standard V-Wheels sometimes require an additional bracket to properly space them from the rail they run on, the Mini V-Wheels are able to mount on the Actobotics 1.5" pattern which can be found on nearly any Actobotics part. Use Mini V-Wheel Standoffs if you're installing the wheels onto a part with thru-holes (such as channel) or use Mini V-Wheel Spacers if you're installing onto a part with threaded holes (such as a pattern mount). Mini V-Wheels are sold individually and come with a pair of pressed-in 5mm ID ball bearings to get you up and rolling!