If other monitoring options have been exhausted or the risk of discovery is too big to perform direct active monitoring in the building, this Digital stethoscope recorder PKI 2115 is used. Here, too, PKI sets international standards. This lightweight 20g digital stethoscope recorder including piezo transducer is fastened at walls/windows, door frames as quick as lightning using the new „adhesive paste“. As a result of its small dimensions of only 9 x 23 x 63mm this is possible inconspicuously. Playback is realized via a laptop or directly with the delivered earphones. Conversations can thus be recorded through walls and windows at any time without effort and difficulty using the PKI 2115.