Only limited suitability for devices with automatic USB / AC adapter detection.

Although this product is sold primarily for use with Apple devices, it is but, apart from the cable to a universal 12V / 5V adapter. Therefore, here is a note for potential buyers who do not only have Apple device and want other smartphones load it.

Many devices detect whether they are connected to a USB port or a power adapter. 230V power supply units for example connect to the USB data lines to each other. In the PowerBolt Duo is the case neither in the 1A still in the 2.1A port.

As a result, the connected devices are loaded only with much less power than would be possible.
My HTC HD2 example loads only with 200 mA (according displaying Spoon batch at about 50% battery charge). After I had tinkered myself an intermediate adapter that connects the data lines to each other, the charge current increased with the same battery level to more than 800 mA.
Samsung Galaxy devices to behave similarly.

In principle, the battery is of course at some point fully even with the lower charging current, but it takes much longer and if you not only loads the device, but might also be used for navigation, it can happen that you still with discharged instead charged battery on target arrives.

In the case of Windows Mobile, the charge current ranges with me just so to preserve the battery charge level of, but when I use Android, then it's not likely.

Yet complicate matters to the dependence of the charging current from the charging status and temperature of the batteries. With increasing load and temperature of the charge current is reduced. This of course makes the PowerBolt but not the load Logic in the connected device (smartphone). It can happen in spite of short-circuited USB data lines that the phone is hardly loaded, because it gets too hot through use and possibly direct sunshine. But, of course the PowerBolt nothing ...

Tip 1:
Android 4 is described in "Settings -> Battery" on what has been recognized for a connection. The status is either "Loading (USB)" or "Loading (AC)" or something similar appears. Probably there is also a corresponding display option for other versions of Android.
There are also apps that indicate the battery state, even also with an indication of the power consumption / charging current.

Tip 2:
For Windows Mobile users, there is the free software "Spoon Charge". This indicates the current charge current. It also shows the connection status "USB" or "AC" on, this ad was wrong with my HD2. It was also displayed when connected to the USB port of my PC "AC".

Tip 3:
There are other providers of special micro-USB charging cable, in which the data lines are connected. This saves the tinkering. These cables are of course then only for charging and not for connecting to a USB port!

Mechanically makes the thing a good impression. It fits perfectly into the socket (Skoda), does not wobble and has always Contact.

Addendum [16.9.2012]
I now also own a Samsung Galaxy Tab 7.7 and can therefore report that the same is true for successful store, as for my HD2.
Without shorted USB data lines is not loaded. In the battery level icon is a red cross (quasi as strikethrough) appears. Only with the short-circuit adapter the same charge icon is shown when connected to 230V AC adapter and Tablet invites (at 2.1A port).
I use here the supplied original cable.
My Tab runs on the original Samsung Android 4:04.

Without guarantee the following tip:
The article "adapter (USB) for Samsung Galaxy Tab" here at Amazon seems to me after reading the reviews the universal solution for all non-hobbyist and non-Samsung-Tab-owners to be. However, I have not tried it. Presumably there are still dozens of similar adapter, but this is the first one I've found.