Garmin 12/24-Volt Auto Adapter with External Speaker for GPS Units External speaker with 12/24-volt adapter cable This accessory is a replacement for the 12/24-volt adapter cable with external speaker that came with your StreetPilot 2610/2650. It allows you to power your unit off the vehicle's battery and hear the voice prompts. So if you need a new one, don't delay. You'll be lost without it.