use this wheels to act as part of the joints to transmission power to pull a section of a leg. as seen in the photo, the cockroach design has six legs, each with 4 joints most with 6 degree free movement. each joint needs at least 2 SMA muscles to move. also the belt need to turn 90 degrees in some sections, this need too large pulleys. it is too much work. now decide to make a giant ride-on human hand, use the current legs as fingures, as in a real hand, each joint needs only 2 degrees of free movement. so made this t5 pulleys, much smaller than those used on the cocky's legs. theres is plug in one of pulley, which acts as support platform, need to be removed for the bearing.