+1Anker...Buy through Amazon.
I couldn't recommend this enough
https://www.amazon.co.uk/dp/B00OJXVDAU/?tag=cliospnet01-21
It lasted me a whole 5 days away when I went on holiday last year. They can charge a smart phone 8 times over and the dual port is very handy especially if you're with a mate, charged mine and @leeds2592 phone at CSF this year. Epic thing.
The reviews say it all!
Do these have a limited number of charge cycles before they're no longer effective?
Do these have a limited number of charge cycles before they're no longer effective?