The PKI 2590 Ear Receiver for Covert Operations miniaturised high-tech communication system enables crystal-clear voice transmission. The built-in microphone also serves to enhance auditory perception by amplifying ambient noise during covert observation. If individual, personal settings are required, this is possible by the PKI 2590 Ear Receiver for Covert Operations via the in-ear receiver’s programme interface and the corresponding software application. The software can be used to adjust the overall volume and the volume of the ambient sound reception. The new, automatic design or smaller housing with optimised curvature sits lower in the ear, which improves wearing comfort and stealth.