mAh stands for Milliampere-Hour which is one thousand of ampere hour. This technical term lets you know how much electrical charge the battery holds. The average smartphone needs about 1,500 - 3000mAh to fully charge. The Solar Power Banks that are 5000- 12,000 should be able to fully charge most of your electrical devices.
Figure out the mAh of your electrical devices and find a WindSoleil Solar Charger that can supply the amount of energy needed. Also consider what you would be using the solar charger for before you choose. If you are going to be outdoors for a long time moving around you should consider getting a solar charger with more mAh so it could have more power stored just in case of emergency.
Each power bank holds a different amount of power, whether that is 1200mAh, 5000mAh, or 10,000mAh it may vary. All of the chargers show the amount of mAh it holds.
**Remember if the Solar Charger does not have battery bank in the title it does not have a battery inside. As some of Chargers just use the light to directly charge devices without storing any of the power.