The Sennheiser IE 400 PRO dynamic, in-ear headphones for wireless monitoring systems offer musicians, DJs, and sound engineers a rich listening experience with clear, studio-like accuracy when performing in quiet to moderately loud stage environments. With a secure, comfortable fit rivaling custom-molded models for isolation, the IE 400 PRO shields the user from excessive-stage volumes and poor room acoustics to deliver punchy sound with the transparent midrange. Made to exacting specifications at Sennheiser's German factory, the clear IE 400 PRO features elegant, low-profile housings that are built to survive the rigors of live gigging, while providing a secure, comfortable fit so you can wear them for hours without fatigue. With the IE 400 PRO monitors, you can forget you're even wearing in-ears and feel more connected with your music and the audience, allowing you to perform at your best. The Mackie MP-BTA is a Bluetooth adapter cable with MMCX connectors for Mackie's MP Series in-ear monitors, giving you the convenience of wireless freedom when you want it. The MP-BTA utilizes Bluetooth 4.0 to enable easy, reliable pairing with Bluetooth-enabled devices such as smartphones, tablets, and laptops. The in-line microphone and remote control allow you to take calls, adjust volume, and control playback without having to pull out your mobile device. To use this bundle, simply disconnect the earpieces from the original cable and connect it to the Mackie MP-BTA Bluetooth Adapter with the MMCX connector.