Yeah, the NIMH means nickel metal hydride. I edited the post to add AA in there so it would be less confusing. I actually had the OFNA rechargable receiver pack on there already, it has a pretty high MAH rating (pretty much equates to long lasting) and its cheap. If you can avoid it, never use alkaline batteries anywhere in your R/C car or transmitter. They don't last anywhere near as long as a good set of NIMH batteries of the same size.

EDIT: I acutally sold my KX a couple years ago, and just kept the screen name because I was already using it for everything else. Now I have a 2003 YZ 250, which I am hopefully selling in November to get a 2006 YZ450F. But my KX was the best bike for its time(1998).