The BT-505 is a dual-mode(BR/EDR + Low Energy) USB Adapterand using Realtek RTL8761BUV chipcomplies with Bluetooth 5.1. It combines a BT Protocol Stack for LM, LL, L2CAP, GATT, RFCOMM, SPP and LE.
The BT-505 is compatible with previous versions, including v2.1 + LE for BR/EDR, it allows multiple active links in either slave mode or master mode. For Low Energy, it supports multiple states and allows multiple active links in slave mode. A BR/EDR link and an LE link can be active at the same time.