Surly Monkey Nuts v2.0
These useful little bits are for Surly frames that have rearward-facing horizontal dropouts (i.e. track ends), like the Karate Monkey, ECR, Troll or Ogre. They prevent the wheel from moving all the way forwards in the dropouts, which is useful when you have a front derailleur clamp that would be fouled by the tyre.
Set of 2.