The Sennheiser EW-D SKM-S (R4-9) is a digital wireless handheld transmitter body from the EW-DX series, operating in the R4-9 frequency band (552 to 607 MHz). Sold without a microphone capsule, it features a threaded connector that accepts a wide array of interchangeable Sennheiser and third-party capsules (such as the MMD series). A defining feature is its integrated mute switch, allowing the user to instantly and silently cut the audio output—a critical function for broadcast, theater, and presentations where quick, unobtrusive muting is required. The transmitter body is constructed from durable metal and includes an OLED display for clear feedback on settings and status.

Leveraging the advanced technology of the EW-DX platform, it provides 24-bit/48 kHz digital audio transmission, ultra-low latency, and 128-bit AES encryption. Powered by two AA batteries, it is designed to pair seamlessly with EW-D series receivers. This flexible transmitter body is perfect for sound companies, rental houses, and professionals who maintain a collection of microphone capsules and need the versatility to swap them for different applications, all while benefiting from the convenient mute functionality and premium digital wireless performance.