Modern Vespa

Figuring I could save a little packing space when I'm on the road, I picked up one of those USB plugs that fit into a 12V receptacle. I didn't look at it too closely, it was an impulse buy from a bin at the cash register. Now that I'm home, I'm wondering...

There are two receptacles on the USB end, one marked 1A and the other 2.1A. Which one would I used for my RazrM? Or my Garmin Nuvi 550 for that matter?

I tried to find a simple answer regarding the phone with a web search, but I couldn't find anything clearly definitive.

Or did I just waste my money.

I doubt it will be a waste or detrimental. It will however affect how quickly a device is recharged. Some of the latest phones for example need the 2.1 v to charge effectively.

I've heard the 2.1 mentioned most often in regard to my Razr M.

So neither receptacle will cause harm, which was my biggest concern, but one may work better than the other. Do I have that right?

The amperage rating is a maximum available, not the amps that will be "forced" to your device. Thus, use the port that is greater than or equal to the output of the charger that came with the device.

Typically, a charger like this has two different port outputs to allow at least one 2.0A or so port on a circuit that is limited to say about 3 A total across all ports. Thus, the typical higher demand device can be charged along with a lower demand device.