Here's what other sites are saying:
The 14 hour bus from Paris to Berlin requires a lot of Netflix, but with only an eight hour battery life on your tablet, you bring along the sleek, Goal Zero Sherpa 40 Recharger so you can binge your favorite show as you cruise through the German countryside. If your phone starts to run low on battery as well, you can plug it in to one of the included cables even while your tablet is charging so you'll never have the stress of dead devices when you're trying to navigate a new city. The seamless aluminum body is not only aesthetically pleasing, but durable as well so you can take it with you through multiple countries. After you've drained all the life from the Sherpa, charge it with the solar Nomad 14 or 28 Plus, or plug it into the wall for just under eight hours before you hop on the next bus from Berlin to Amsterdam.
Goal Zero Camp & Hike Sherpa 40 Power Bank Micro Lightning USB-C Black 22030. 8A USB combined outputs ideal for charging power-hungry devices like tablets. Includes USB-C micro USB and Lightning cables for convenience.
Built for charging power-hungry devices like tablets, the Goal Zero Sherpa 40 power pack comes with USB-C, micro-USB and Lightning USB cables for maximum convenience when you're on the move.
Goal Zero Sherpa 50 Power Bank
Goal Zero Guide 10 Plus Recharger
$30 - $39
Seattle Sports SurviVolts Power Bank
EasyAcc 20000mAh Rugged Power Bank
EnerPlex Jumpr Slate 5K-L
Duracell Instant USB Charger