I needed a knob for an 8mm bolt for a fence flip stop that I had designed. My previous 8mm knob was a little too wide and wouldn't let the face flip completely up. So I created this one. Instead of wings for grips, I just added a series of 8 cylinders around the main body. There is a little slack in the hex space, but that's because I've found some bolts with slight variances. The bolt head or nut will only turn a minor amount before seating properly.

My earlier version had too wide an opening for some people's use, so this should alleviate that issue. The 8.1mm diameter hole is snug enough that it may take a little pressure to fit the bolt through, but it goes. The body is still intended for a 20mm dog hole.