A screw plug kit for tire repair.

Screw plugs are the fast version of a trail puncture repair: thread one into the hole and it seals, without the reaming and forcing a conventional plug needs. On a small puncture you can be moving again in a couple of minutes.

Cheap enough that there is no reason not to carry one alongside a full plug kit — different punctures suit different repairs, and this one handles the easy majority quickly.

As with any plug, this is a trail repair. Have the tire properly inspected once you are home.