Not bad.

The Sennheiser FW9 Bluetooth headset adopts an in-ear design, which is soft and comfortable, and almost no sensation when worn for a long time. It is also equipped with a polymer composite diaphragm and ACC high-definition audio codec technology, which can bring high fidelity In terms of sound quality, the mid-frequency vocals are closer to the face, and the high-frequency instruments sound transparent. The headphones also have features such as low latency and noise reduction, which can bring a better listening experience.