Now, these Sungale Power Disks are a 'portable' power charger, but personally I found that they were a little trickier to keep a couple with me as I walked around, in the sense that they may not fit in your pocket as easily as others out there, plus as you stack them up it definitely limits the carry-around factor. If you had a purse, or a jacket pocket, or a messenger bag, they fit very easily.
Some might still like to carry them around, but I think the big draw on these guys are the fact that they're stackable. I like that. Plop one on top of the other and you've now doubled your power reserve.
For me, the use of these power disks has been as an alternate to my work laptop usb cord. A laptop can sometimes put out 100mA to maybe 300mA for power. That means it's going to charge real slow. Which is okay if you don't need power quickly... put it on and let it charge until the next meeting. But I hate doing those long, slow charges. I usually notice "hey, it's low, better charge it before I go". For that I need to be able to have something that uses more current. Most adapters that phones come with are 500mA, some are even 1A (I like those). The cool ones are 2A.
These power discs are rated at 1A. So I can get a quicker charge than my laptop... then, just plug them in at night and charge up what I used (or get a couple days out of the stack).
I've been finding charging my phone has been about 30 minutes for a 15% bump in the battery. Which I think is pretty good. Now charging them up is a little bit longer... especially as I'm using my laptop for it, but ... set it up to charge over night. Who cares, I may drain them by the end of the day (hasn't happened yet, even for one stack), but click it on to the computer and it'll top itself up by the time I get back 16 hours later easily. I'm usually using up one per day, so after 2 days I'll charge the duo up.
What I like is that it senses the connection and starts charging automatically - but if it doesn't for your phone, just hit the button (the little battery icon... it doesn't feel like a battery as it's pretty flush with the case, but you can push it in).
Now, you can easily find their 'square' version online, but for the round ones, I've only been able to find a pack of 3 for $70 (which comes with the wall outlet, which the box I reeived didn't come with). http://www.qvc.com/Sungale-Set3-3000-mAh-Stackable-Cell-Phone-&-Tablet-Chargers.product.E225918.html?sc=E225918-User&cm_sp=VIEWPOSITION-_-1-_-E225918&catentryImage=http://images.qvc.com/is/image/e/18/e225918.001?$uslarge$
But here's their site info on them
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