DRUM® Compact Portable (CP) Radio
The DRUM® CP Medium Frequency Radio is a battery powered, digitally controlled, analog frequency modulation, single-channel voice communication radio. It uses a two-element omnidirectional magnetic induction antenna operating in the medium frequency (MF) band to propagate its signal parasitically across metal infrastructure in an underground / tunnel environment. 
Under normal operating conditions, signals can be relied on to propagate many miles between the sending radio and any receiving radios with little attenuation. In post-incident emergency circumstances, when conductive infrastructure has been altered or damaged, the units can be moved to propagate their signals on surviving conductive infrastructure, forming a survivable redundant communication path.
The DRUM® CP is compatible with the DRUM® Repeater Units, in that it can send and receive voice transmissions interchangeably with the DRUM® Repeater's MF interface. The product is lightweight, rugged, and man-portable.
DRUM® CP - Features
Lowest Cost-Per-Foot of Any Communication System on the Market - By Far
Fulfills the MINER Act Requirement for a Redundant Communication System
Seamlessly Interoperates with Existing UHF / VHF Leaky Feeders and Handsets
Supports Point-to-Point Voice Range of Over 5 Miles Underground
Communication in hard to reach spots, temporary working areas, and bleeders