Pioneer FX Select Knob DAA1213 DJM 700/750/850/900/5000, DDJ 800/1000, XDJ RX/2
 
Single Pioneer Select Switch Cap (DAA1213) 
 
Replacement part
 
Compatible for Pioneer Mixers
DJM-700, DJM-750, DJM-750Mk2, DJM-850, DJM-900, DJM-900SRT, DJM-900NXS, DJM-5000
 
Compatible for Pioneer Controllers 
DDJ-800, DDJ-1000, DDJ-1000SRT XDJ-RX, XDJ-RX2
 
This is not an original pioneer part, but it is the same size and shape.