At enormous expense I bought the "correct" DJ Techtools tools knobs for my S4 Mk3.
My advice, don't bother, go online and get some Chinesium Chroma knobs off ebay. The Dj Techtools knobs don't fit properly i.e they simply do not go down on the pot shaft all the way, and I mean every knob, not just the odd one.
The Chinesium ones are a lot easier to get on or off, fit flush down into the pot recess AND are cheaper too - just make sure they are for NI controllers.
