Three different models are known, one designed for the Mark V[B], another for the Military Police helmet, and an Up-Armored variant for the ODST Helmet. The former are standard issue to Special Force unit commanders and Beta-5 Security units patrolling the Inner colonies, while the latter seems to be exclusively used by the ODSTs. The three devices differ in appearance as well as their pricing.
The CNM is available as a helmet accessory in Halo: Reach. The device for the Mark V[B] costs 2000 cR, while the one for the MP variant is priced at 5000 cR, and the ODST variant is priced at 1000 cR.