It's the 1S CRC shorty pack 4200 / 65C
http://www.stormerhobbies.com/cgi-bi...=cs&pn=CRC3703
The good thing about this pack is that it is the same size as 3 sub-C cells rather than 4 like the standard 1S packs, so it fits better in the l3. I had also tried off-road saddle packs, using just one, which makes it a 1S and are the size of 3 sub-C's as well, but they were taller, and put more weight on one side.
I had used the Speed-Zone 1S saddle packs, they are good.
The CRC pack is really nice for T-plate cars if your running 17.5T class, which I do.