Good shop and trailside mechanics know how to avoid damaging the rim while doing a tire change or tube repair.

These trick Plastic Rim Protectors clip onto the rim edge to prevent  damage to your aluminum rim surface.

Cosmetically this is great but more importantly they prevent those nasty little shards of metal that can be scraped off the rim surface (by the tire lever) and end up inside the tire. This can ultimately cause puncturing of the tube.

Cords to keep the protectors from getting lost inside your tire are included.