Castle Creations Castle Link Quick Connect Duo

Installs between ESC and receiver and prevents loss of settings
when unplugging Castle controller from receiver
Detects the presence of Castle Link adapter on the free lead and
switches controller's signal line from receiver to Castle Link
Supports all Castle Link capable ESCs, but is designed specifically
for use with Castle ESCs featuring AUX wire technology

Castle Link Quick Connect with Receiver Connector and Castle Link
Connector

Quick Connect Duo will work with the Field Programming Card when used
as a standalone programmer. It only works when using the Field
Programming Card as a Castle Link adapter.