Gone in 60 seconds: stuff that sells instantly

There seem to be particular items that always sell within minutes, every time they come up on the LFGSS classifieds. For no particular reason, I'm starting a list with idle speculation on why:

1. Wheel truing stands - everyone likes sorting out their own wheels, but doesn't do enough of it to make it worth buying a new stand
   
2. Pizza racks - front racks in general sell pretty quickly, but these always sell straight away. I reckon that people like the idea, but don't know whether they'll get on with them and don't want to shell out on a new one in case they don't.
   
   

Any others?