This is an RS-232 interface cable for use with the bridge for setup and also to allow the bridge to accept RS-232 ASCII data and post it as keystrokes to any device that supports Bluetooth HID (aka keyboard mode)
The power & charge the bridge with this USB to RS-232 adatptor cable.
Get the USB to RS-232 adaptor with power on PIN9 for use with the bridge cable (and more).
It can also be used to enable data the bridge is posting, to be monitored by a 3rd device either via RS-232 or via Bluetooth when using a BlueSnap RS-232 dongle.
These cables are RoHS compliant.