The most reliable USB inserts I've found come from SCOSCHE, and pictured here is the USBC242M. I have tried & murdered many as well as lived vicariously through customers failed products too. The white colored Rayovac USB charger, used in this test, died shortly afterwards.


The SCOSCHE USBC242M is 12 Watts or 2.4A per port (24W - 4.8A total output) and is the one you'd want. The older model SCOSCHE was 2.1A per port.


SCOSCHE USBC242M (LINK)


I have ordered a fair number of the SCOSCHE USBC242M for customers and not yet had a single one fail. I believe I have approx 45 of these out there, in use, without a failure to date.


My family regularly charges two iPad Air's off just one USBC242M. We keep 4 of them on-board, three at the nav station and one in the v-berth. We also use them in each car.


Times are always changing and I am sure there are other reliable USB chargers out there now. Look for one that offers the ability to charge your product at "high speed" and can deliver at least 2.4A per USB port. Buying a well known name brand seems to mean squat in this product arena. Below are some of the USB charger failure brands I have seen.


USB Charger Failures:


Belkin
RCA
Griffin Technology
Rayovac
Anker
Blue Sea (dual socket permanent mount)
Duracell
No Name USB = Lots