Very similar to the older Samsung chargers, like the ones that would come with The Galaxy Tab A or pre S5 series phones back when 1-2 amps was plenty for your phone.A 2 amp charger only puts out 10 watts @ 5 volts, modern chargers that use fast charging and whatnot can switch between 5 and 9 volts. This charger can switch to 9 volt / 1.67 amp for a max output of 15 watts.Modern phones want more than 10-15 watts. They want about 30 watts to rapid charge, or to be able to charge while in use. Amps x volts = wattsso 3 amps @ 9 volts would be 27 watts...and so on.Hence the reason modern chargers are specifically in watts.All that said, I'm using these to power LED neon style wall signs. 4 devices on one charger via a USB hub. 10 watts is more than enough.Highly recommended, but NOT for smartphones.ALWAYS REMEMBER, COMPATIBLE DOES NOT MEAN ADEQUATE.