What frequency does Catchbox mics work on?

Different Catchbox microphone models work on different frequencies:

Plus 
uses the license-free DECT 6.0 (1.8 / 1.9 GHz band) transmission standard that has a clean and uninterrupted signal.  

Mod

requires a 3rd party beltpack system. The frequency depends on the particular beltpack system.

Legacy Plus

uses the license-free DECT 1.7 & 1.9 GHz transmission standard that has a clean and uninterrupted signal.