For me the best external battery either level quality, design, price ...
Some will complain about its size / weight but for this ability there, its size is quite respectable and no one can clearly make smaller then at that price and the production quality was really nothing to complain about !!!
Delivered in 13 days (respectable) with a small silicone case to protect it from scratches etc.
Otherwise does his job (and allows charging / charge simultaneous)
From a personal view, I advise eyes closed.