Bests & Worsts Reviews from Amazon

All Lithium batteries are 20-25% off the mentioned capacity: If you don't care why you should skip this section!!! ********************************************************************** A little good-to-know fact on batteries: Lithium batteries are 3.7 V and USB ports are 5V, to convert 3.7 to 5 you are gonna lose some juice- about 20-25% of the battery's mentioned capacity. That means the actual capacity here should be around 7500 mah (again, almost all batteries actual capacities are 75-80%). ********************************************************************* You can see that by seller description: 2.5 time Samsung galaxy s8 is 7500 mah. good thing is that I checked the actual battery's capacity and it is really 7500 mah- so the seller is obviously honest here. PROS: - It is really small! see pics - actual capacity tested for 7500 mah. - can handle 2V both when charging or being charged. - it came with nice case and perfect length micro USB cable (pics) - It also works with apple: tested on iphone 7 and 8+ with no issues CONS - you are paying mostly for the compact size (at this price you can get some quick charge batteries). - input is 2A, so basically if you know your charge can do 2A it's gonna take 5-6 hours to charge it, otherwise, its gonna take 10-12 hours by 1A charger or a full day via computer port. summary: If you want a 7500 mah compact size battery you can carry in your pocket this one is the real thing. If you care too much on charging your phone fully in an half an hour- you should probably look for a battery compatible with your phone's quick charge standard.