I've seen these items many times and often thought about @Court droning on and on about no place to mount a rack or water bottle. Maybe everyone knows about these, but thought I'd post it anyway.
For people with the real need, there is also a ThreadCert tool and insert set. I own one of these tools for marine applications and they work very well. The one I own does both stainless steel and aluminum. I've seen many bicycles with these type of "braze-ons", I've never used them on a bicycle but have on motorcycles, pickups and boats. I wouldn't hesitate to use on a bicycle if I had the need.
. Maybe everyone knows about these, but thought I'd post it anyway.
