From Techgearlab.com

The Clutch is easily one of our favorite portable chargers for iPhone users. Its slim and minimalistic design makes it particularly convenient and easy to carry around, and the integrated charging cable means you never have to worry about forgetting one. It can be exceptionally handy to the iPhone user who always finds their phone close to dying at the end of the day and never wants to be caught with a dead battery.

• Magnetizes to magnetic-safe cases * More power (5,000 mAh) * Built-in charging cable / no extra chords to carry * Small and lightweight, weighing only 3.5oz * LED indicators for increased convenience * Easy to store in some wallets, purses and back-pocket * Also charges small USB-C port devices (e.g. Kindles)