This hub adapter lets you connect Actobotics parts with a 0.77" hub pattern to parts with a 0.625" hub pattern. The holes for the 0.77" pattern are un-tapped whereas the holes for the 0.625" pattern are tapped. These adapters are ideal for mounting two different hub patterns: mating hubs to gears, sprockets, or wheels. Actobotics is a robotics building system based around extruded aluminum channels, gears, precision shafts, and ball bearings. Thanks to the two standardized hole patterns, nearly all Actobotics components can be intuitively connected together. The wide range of components makes building complex electromechanical prototypes or finished projects a reality.