it says its silver oxide, it is probably very potent.
hearing aid batteries that are silveroxide can last 3 times longer than alkies, in high drain devices.
on the OTHER hand, silver oxide is used more often in devices that have a low slow draw, for longer runtimes. so it might voltage drop if you tried to draw lots and lots off of it.
if the unit it is designed to go into, runs 3-5 5mm leds, then it probably is not such high current (at one time), but longer running. if it was designed to go in a digital camera (for example) it would certannly put out the 6v strongly.
if you stick it in something looking for 3-4V max, it could be to hot for it, depending on the current draw, or curcuit used.
lots of the curcuits that are put in these led lights are very dependant on the voltage input. some (lets call them) better curcuits, as long as it is within the voltage range, the current to the led would be similar.
i am not helping am i