Surly says...... Front derailleur clamps are sort of bulky. The space between the tire and the seat tube on the Karate Monkey frame is relatively tight. This means that sometimes on a KM the rear tire can rub the front derailleur clamp. Monkey Nuts clamp into Surly horizontal rear fork ends (aka dropouts) to make spacing the wheel back easy. Just install them then install the wheel all the way forward. Bang, done.

Monkey Nuts v1, QR/10mm Bolt-type axles - Pulls wheel back 5mm in dropouts
Monkey Nuts v2, QR/10mm Bolt-type axles - Pulls wheel back 14mm in dropouts
Monkey Nut v3, Thru Axle/QR/10mm Bolt-type axles - Pulls wheel back 12.5mm in dropouts

Bikemonger says....... Note that v1 and v2 come in pairs but v3 comes singly making them twice as expensive. Weird we know, but we double checked and that's the way it is.