The PKI 2425 Digital Wireless Earphone receives the digital data of the PKI 2430 Digital Wireless Transmitter in the GHz range up to a distance of 10m. This combination is applied wherever bug-proof, wireless digital data transmission is desired in the short range. The transmitter has already been integrated into many PKI devices; then only the earphones must be inserted for transmission. This is particularly important for camouflaged monitoring operations. Without integrated transmitter, PKI 2435 can be externally connected and activated via a 3.5mm phone jack.