This 27:1 ratio worm gear set provides a compact way to create a drastic reduction in the output speed of a gear motor. The 1/4" D-bore of the stainless worm will allow it to mount on a 1/4" D-shaft which is used throughout the Actobotics build system. The mating worm gear mounts on a specialized Steel 1/4" D-Bore Barrel Hub for Worm Gear to create a reliable junction between the gear and the shaft it's turning. The worm and the worm gear are designed so that you can run them 0.75" apart from one another; the same spacing you'll find on Actobotics Channel and other components within the build system. Aside from the massive reduction in speed and the increase in torque, these worm gears will lock in place when at rest so you don't have to worry about an outside force backdriving the mechanism driving them.