This gear bearing holder is by default made for holding a 1.6cm gear bearing. The file is in .stl format and you can customize it to suit other size of gear bearing. You can see the video demonstration on how to install it via this link http://youtu.be/6PNzOFl1w2M you can also visit my gallery for more of my work here -> http://bidtocart.com/3d-gallery-free-downloads/ If you like my work please like me at my facebook https://www.facebook.com/bidtocart