http://www.hangtimes.com/sportrxpacks.html

GP 1100ma 4.8v NiMH 4 cell Mini Ignition and Reciever pack. Ideal for systems needing very high capacity while remaining smaller and lighter than any standard AA OEM dimensioned pack. Super small, Super high capacity, very low internal impedance. Same dimensions as the Sanyo 500A nicad with TWICE the capacity with half the impedance of a AA pack. This is an outstanding choice for a lightweight ignition pack with the punch to handle the loads. Also an excellent choice as a Rx pack for .40-.60 sized aircraft with high torque servos. High-Rate NiMH engineering designed to deal with high current loads without the typical voltage drop common to AA sized cells.

Single cell dimension: .67 x 1.1
Finished pack weight, inc connector: 3.3oz $23.95
Internal Impedance: 7 mOhms