Couple months ago, we had a party in the apartment and somebody lifted my OE charger for my Maxx. I've been using my Droid X charger which is 5v/850mA output. The chargers listed on Moto's website are displayed in Watts and Amps. I didn't look much into the conversion, but I assume that one of these chargers would be the most efficient for out phones?
Dual Port Charger
Duo Rapid Charger
Dual Port Charger
Duo Rapid Charger