I've been putting off posting this, hoping to remember where I bought them a few years ago. Danged if I can recall...NAPA maybe? Pretty sure they were either Camel or Monkey Grip branded. I recall that I had not seen them in many years so I bought them when I saw them.

I've only ever used them on tubeless tires. In that case you don't have the clamping action of the tube against the tire.

I also have a couple of the special clamps that allow one to hold them in position before touching them off.

One advantage is that they have a very long shelf life, unlike the glue.