Can I charge 2 devices from the GPS socket?

[Doberman]

I am expecting delivery for a Zumo 660 and I am planning on using the canbus GPS socket for charging it. I would also like to use the same socket for charging my iphone with this little baby here: http://www.burnsmoto.com/usb-power-socket-weatherproof.php

I want to believe that there would be no problem for such small devices, but there is no harm in double checking.
Thanks in advance.

 

[Wapping]

If it has the same same power limitation of 5A as the other auxiliary sockets, you will be fine.