The Speen Umlenker is a little metal bracket used to convert a bottom pull road front derailleur into a top pull derailleur (typically for use on a MTB).
There are a few different versions depending on the front derailleur you want to adapt so make sure you order the right one.
Pictured below is the version for Dura Ace FD7800 derailleurs (these will work with a triple ring front on a MTB):