CSR 4.0A dopt CSR8510 chip which is in line with Bluetooth 4.0 technical specification and dual mode transmission. USB 2.0USB 2.0 interface is more versatile. Fully backward compatible with Bluetooth 2.0 Bluetooth 2.1 Bluetooth 3.0 specifications. Lightweight and ultra-mini & portable. 20m Transmission Distance &3Mbps Transmission RateLonger transmission distance (no barrier) with strong signal. More stable transmission rate providing high-speed file and audio data transmission. Connected Devices(Includes all Bluetooth v 4.0 /v 3.0 /v 2.1 /v 2.0 /v 1.1 devices): Bluetooth headset/ PDA/ Mobile phone/Keyboard mouse/ GPS positioning system/ Printer/Laptop/Other Bluetooth devices/Desktop computer(P. S. For MAC system can only be used in versions 10.2 - 10.84. )For CSR Original Drive Management SoftwareFor CSR Harmony drive management software is easy to use powerful and supports a variety of application extensions (For Microsoft OFFICE software). Ultra-low latency speed connection intelligent sleep wake-up energy saving 24-bit CRC check to resist interference adaptive frequency hopping to reduce crosstalk.