mAh
Milliamp Hours.
A unit for measuring electric power over time. mAh is commonly used to describe the total amount of energy a battery can store at one time.
A higher mAh rating means the (fully-charged) battery can power a
device that consumes more power and/or for a longer amount of time before becoming depleted and needing to be re-charged. For example, a battery rated at 1500 mAh can power a
device drawing 100 milliamps for 15 hours, or a
device drawing 150 milliamps for 10 hours
Sidesho batts (automatics) say .59 WH so I can only assume that means 590 mAh. No idea what the Blu batt is rated at as I havent torn one apart yet.