Some p-clips to replace the broken one which is no longer holding my rack onto my commuting bicycle.
These are actually the correct size for my seat stays, so should be relatively easily fit, and more solid and longer lasting. If they fail, I can replace them a further 1½ times, since I bought five!
The second one did successfully hold the rack on the bike, by itself, all of this week, although I suspect it's been stressed more than would be reliable for very long.