These batteries are a very good value, They have a protection circuit built into the base. When checked they may not be 4000 mah as advertised but about 3500 mah plus. After a few charge/discharge cycles they may be 4000 MaH. The protection circuit board may limit full current draw but they work very well in the 7 led SKYRAY flashlights I have which use 4 of these cells in parallel which works out to 16,000 MaH. Good bright light. Long duration . Still strong after 1.5 hours/
When placed in the center of a room they produce 430 LUX (MEASURED WITH A LIGHT METER) under the beam reflected from an 8 foot ceiling. Bright enough to read a book by. and ideal when power goes out. Happened here recently.