FN Five seveN Compatibility:
DT-CAOS is compatible with the FN Five seveN MK2.
DT-CAOS is not compatible with the first four FN Five seveN generations.
The easiest way to identify if your Five seveN is compatible is to look for charging serrations on the front of your factory slide. Please see the chart below. Only the FN Five seveN MK2 has charging serrations on the front of the factory slide cover. In contrast, the original Five seveN, tactical, IOM and USG all have a smooth surface on the front of the factory slide cover.