In addition to providing traditional Sennheiser sound, these headphones are compatible with the aptX codec for textured playback. They also support the AAC codec, providing high-quality audio for iPhone users. This is an updated model of the HD 4.40BT, which won the most prestigious VGP Award in Japan in this category. Compatible with the aptX Low Latency codec, allowing you to enjoy videos and games without sound delay. Stable connection via Bluetooth 5.0 and Class 1. Long battery life for peace of mind during commutes or travel: 30 hours of continuous use with a 1.5-hour charge. USB Type-C charging cable for fast charging. Compact size allows you to enjoy music anytime, anywhere. Supports hands-free calling. Supported voice assistants: Siri, Google. Dynamic/Closed-back. ● Sensitivity: 108dB (1kHz/0dBFS). ● Frequency response: 18-22,000Hz (-10dB). In addition to providing traditional Sennheiser sound, the upgraded HD 4.40BT is compatible with the aptX codec for textured playback. It also supports the AAC codec, bringing high-quality sound to iPhone users. This model has won the most prestigious VGP Award in Japan in this category. Compatible with aptX Low Latency, which provides sound without delay during movie viewing and gameplay with a stable and stress-free connection via Bluetooth 5.0 and Class 1. Multi-point support allows simultaneous standby on smartphones and PCs at work and for personal use. Long battery life for peace of mind during commutes and travel: 30 hours of continuous use with a 1.5-hour charge. Fast charging is possible with a USB Type-C charging cable. Dynamic type/Closed-back type/Sensitivity: 108dB (1kHz/0dBFS)/Frequency characteristics: 18-22,000Hz (-10dB)/Certified by the Ministry of Internal Affairs and Communications/Frequency band: 2.4GHz USB-C charging cable