A company that primarily deals through Amazon, Anker makes all sorts of USB power supplies and batteries. Personally I have been very happy with their products and service. One of my 5 port, 40 Watt USB chargers had a couple ports fail, and when I contacted Anker to get a replacement, they told me to keep the old charger. I've seen teardowns all over the internet comparing USB chargers and showing why cheap chargers are a bad idea to use. Nobody seems to have shown any real evidence beyond simply reviews of why this particular charger deserves the reviews it gets, so as I have an extra one now it seems like a good time to fix that!