These are a pair of hand knobs designed to fit an M5 nut, and M5 bolt respectively. I find the latter especially useful for light clamping applications and other situations where it is helpful to use a bolt to adjust some distance, but undesirable to need a hex key.

The nut knob has a simple recess for an M5 nut, which can be glued in place to prevent it from falling out. The bolt knob has a recess sized for the head of the bolts I have access to, with a protrusion on the inside designed to emulate a hex key, such that a bolt once inserted is reasonably secure, and can be turned by hand easily.

Note that while the protrusion in the bolt knob is surprisingly strong/effective, it is still a small plastic feature at the end of the day, and will strip/fail to turn under heavy load. Thankfully it simply rounds off the protrusion instead of stripping the bolt, but as a general rule I'd recommend only using it in places where a thumb screw would otherwise be appropriate. For example, in projects where I'd expect a bolt to cut its own threads, I have found that the knob cannot be used to cut the thread, but can be used to insert/remove a bolt once a drill or key has been used to insert it the first time.