The Tag-Along Solar Battery with a USB port to allow you to charge your phone or any gadgets works on inbuilt Li-Polymer battery similar to the batteries found in the mobile phone.It continually stores sunlight on the inbuilt battery when exposed to sunlight. It then keeps this stored power ready to charge your phone or gadgets.This cycle continues every time it is exposed to sunlight. Stored power used is replenished without doing anything when exposed to sunlight. So all you have to do is TAG Along with the solar charger to your backpack or purse and let it charge so when you need it is all ready to go.DETAILS:Stored capacity is 4050 mAh and very lightweight as it will continuously replenish the power that is used. Smart IC controls auto power shutoff when fully charged on both the device and the power bank.Your smartphone like iPhone will charge fully in 4 hours and similar devices will charge in 4 to 5 hours.It can also be charged indoor via USB port and store the power for later use.Will work with: iPhone models - 4/4s, 5/5s, 6/6 Plus, 7/7Plus.8/8Plus, iPhone X, iPad Mini, iTouch, iPod, Galaxy 3/4/5, Note, HTC All, LG All.Check this Video https://youtu.be/X2eONGN_yeE