This is the fourth version of my Treads and they are working well so I decided to upload this one. Included are the x3g file and the skp. The treads are made to lock together to make a completed set. This is the smallest that is should be printed as it is. No need for pins or flex filament all you need to do is print and hook. P.S: There is a little support on the bottom to prevent saging that can come right off by snaping it off or by cutting it. Wow that is not a very good picture of it.