These motors were custom designed by Acroname for use in the Garcia robot. They are extremely efficient, create almost no electrical noise and are quiet in operation. The armature windings of these motors are 6 V windings and work well running at 4-8 V. Higher voltages will eventually compromise the motor quality and could damage them. They have a flat on the shaft for output mounting. Since these are high-quality motors we discourage mounting wheels directly to these motor shafts as they are not rated to withstand high radial loads.