The Sennheiser SL Handheld DW-4-US is a digital wireless handheld transmitter optimized for speech applications in presentations and lectures. Operating on the DECT 1.8/1.9 GHz band with a frequency range of 1920–1930 MHz, it features a supercardioid condenser microphone capsule with a 50–20,000 Hz frequency response and a signal-to-noise ratio exceeding 90 dB(A). The system provides automatic frequency management, bidirectional communication, and 256-bit AES encryption for secure transmission. It includes an LC display for battery status and reception quality, a mute slider, and a rechargeable Li-Ion battery offering up to 15 hours of operation. The unit supports external charging via contact points and includes a USB socket for service purposes.