The ER4XR-BT Wireless In-Ear Headphones from Etymotic Research are made to provide you with reference-quality audio fidelity. They utilize balanced-armature, precision-matched, and custom-tuned drivers. These in-ear monitors also feature a high 122 dB SPL sensitivity, clear midrange and highs, natural bass, and the convenience of a wireless design. To ensure audio quality during wireless transmission, Etymotic equipped these headphones with a dedicated AKM AK4331 DAC and headphone amplifier. They also support aptX, aptX HD, and aptX LL for 24-bit/48 kHz lossless playback.

To deliver as pure an audio experience as possible, Etymotic crafts their earbuds for significant passive noise isolation up to 42 dB. Such noise isolation is ideal for both music and mobile calls. Pair the ER4XR-BT headphones with your smartphone and you can use the built-in mic pod for hands-free calls. The microphone has a 3-button control for calls and audio playback. They last for over 8 hours on a single charge, feature dual shirt clips for keeping them secure during use, and durable metal earpieces with an anodized finish.