Yokes are used on many current model bows to connect the cable to the cam. it helps reduce cam lean. 
Some models using them include:

Mathews Monster, Chill, Halon, Triax, Vertix and VXR series use Two. 
Prime bows use Two for the main string and Two more for the Black series cables (so you would need Four in total.)
Hoyt RX series bows use One. 
PSE Evolve cams use Two