Check the listing for details. FiiO BTR11 Bluetooth 5.3 Receiver /Wireless Audio Headphone Amplifier (Black). Color: Black, Condition: Open box. Listed at 15.99 USD. FiiO BTR11 Bluetooth 5.3 Receiver LDAC 3.5mm Wireless Audio Headphone Amplifier Adapter (Black) BTR11 supports the LDAC Bluetooth audio format, providing HiFi-level wireless Bluetooth sound quality, and also supports Bluetooth 5.3! In continuous music playback, the working time reaches 15 hours. When the battery is low, it only takes 1 hour to charge up to 90%, close to full capacity! Weighing only 12.5g and measuring about 5.5cm, it offers two convenient carrying options: an elastic back clip and a lanyard, making it stress-free to carry! With a built-in high-performance independent ear amplifier and an output power of up to 45mW (16Ω), it allows earphones to deliver excellent performance, providing high-quality music comparable to wired connections via Bluetooth. It features a built-in high-sensitivity omnidirectional microphone that supports call noise reduction, ensuring a clear calling experience. Not only can it turn wired headphones into Bluetooth wireless headphones instantly, but it can also upgrade non-Bluetooth speakers or those that don’t support LDAC to Bluetooth capability or enhance them to support higher-quality Bluetooth formats!