I bought this for my HTC One (M8) and I plugged it in and it works a treat! Capacity is around 59GB which is what I roughly expected from FAT formatting but its certainly big enough and fast enough for my needs.
I have tried to maintain stubble with this but unfortunately you can't as the lowest guide you get actaully just leaves you with hair about 2mm in length. Good for beards though I imagine also great value for money.
Great For Festivals, 6 Feb 2014
I bought this for my sister when she went to V Festival and it kept her iPhone going all weekend. Its a great product but it does take forever to recharge. Still for the amount of power i contains I can't complain.