I just bought a Weller WXMP Soldering Iron and got these two plastic things (pictures) in the package. I have searched the web but can't find any instructions on what to use them for. What are they used for?
They are used to connect more than one soldering iron holder to each other. You can see them in this picture:
Typically this is used when you have a station with multiple soldering irons (set for different temperatures or different tips).
You use the plastic connectors to join the holders together and add a little space between them.