brick shafts are LEGO® compatible shafts that you put on any of the knobs. now you may mount any lego part. why not put on a big lego rubber wheel for that extra grip? or build your own motor driven programmable LFO together with LEGO® MINDSTORMS? the brick shaft comes in four colors and lets you experiment with any parameter. it supports any idea you may have that involves LEGO® bricks. available in 4 colors.