Very very good rechargeable batteries made in Japan by Eneloop that manufactures the best nimh batteries in the world. A 4 3.50 is a bargain!
UPDATE 25 April 2014: Now that Amazon has spent the price of 3.50 (they only stayed a few days at this price obviously, probably to try to "make known") to 8, NOT WORTH MORE OF CA ALL BANG!
As much as take real ENELOOP so you will for the same price of technology much more recent models.
In short go for 3.50, 8 run away!