This is a shifter knob that can be screwed on to threads that are 12mmx1.75. The STLs need to be auto oriented to print without supports. Printing at a low layer height works best for the threads on the inside to be smoother, as well as the ball being smooth. The ball may be a bit big for some people, and I can edit that if needed. Also if you want this model but with a different thread size, message me or comment and I can upload a version with that thread. The actual "8" parts clicked in with a bit of force and no glue was needed, but you may want to use some if desired. I put a bit of lubricant on the thread to make it easier to spin on and off, but you may not need it.