The POA68 antenna adapter connects the active car kits (e.g. CK02 and CK03) with the vehicle antenna. The adapter is screwed onto the radio between the housing and antenna. When the radio is locked into the car kit, it is connected to the vehicle antenna via corresponding contacts and the range of your radio increases enormously.
The antenna adapter is included in the scope of supply of all active car kits and can also be purchased separately