I use this RADIO SHACK version hardwired into my OFF-ROAD POPUP camper. Has helped us out many times sitting back in the woods somewhere.
This unit works on DC with external xmfr and also has the batteries.
I removed the batteries and use one of those DC VOLTAGE CONVERTER plugs that allows you to set different DC VOLTAGEs when plugged into a 12VDC source.
This is always on in my OFF-ROAD POPUP camper... I like this model as it searches for active WX CHANNEL the instant you turn it on.
I use my SIRIUS RADIO in my truck when in travel mode.
Roy Ken