Technique Belt wheel
https://img07.shop-pro.jp/PA01113/724/product/52054216.gif?20121122161931
https://www.brickers.jp/?pid=30181867
belt wheel
I wasn't sure what it was classified as, so I was looking for it in gear, but it was classified as wheel.
https://www.bricklink.com/v2/catalog/catalogitem.page?P=4185#T=C
Can also be used as 60 degree parts or 120 degree parts since the studs stick in the holes
Belt Wheel Tachikoma
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