Charging up things isn't always that straightforward especially when they're not supplied with the required equipment and it's assumed you have your computer on most of the day to just plug in and leave.
But then you also might be away and not wishing to lug a laptop with you just for that.
Unfortunately quite a number of chargers you find on Amazon and other places aren't so much useless as beeping dangerous having exploded, caught fire and even electrocuted people while using them.
This one by FX Factory was on offer at W H Smiths and is RosH tested and CE approved featuring a regulator that sense when your device is charged and cuts off the charging so the battery isn't overcharged and the voltage doesn't rise suddenly.
I had one previously but it stopped worked without catching fire or anything scary like thta but thought it was time to get another.