It is connected with the main speaker through smartphone, and then the main speakers connect s with the slave speaker via a Bluetooth wireless mode connection, to achieve true wireless Bluetooth for left and right channels separated of Bluetooth speaker.The program based on CSR Bluetooth4.0 with dual-mode module development.  When not connected to the speaker, the main speaker stereo back monomers. It is no delay, and good sound quality. Designed to provide customers with stable performance characteristics of high-end Bluetooth loud speaker programs. It need 2 pcs Bluetooth modules with TWS function to realize it as below.