FDK (formerly Sanyo). Most popular cell for S-280 and S-300 machines. Ultra long duration for GWS IPS powered ships like the Pico Stick and Tiger Moth. Perfect in 8 cell packs for Zero, Mustang and Beaver. Normally used in the 3 to 6 amp range but has applications up to 8 amps for short burst in fun-fly models. NOT for S-400, although I have used one with a lower current 7.2V S-400 setup previously. AAA size cell. Manufacturers listed internal resistance is 35mohm.

FDK/Sanyo Twicell NiMH HR-AAAUC 700mAh Flat top cell Twicell Battery Single Cell 1.2 Volt

Capacity: 730 mAh
Discharge Rate: 1 Amp
Single Cell Length: 1.73"
Single Cell Diameter: 0.41"
Single Cell Weight: 0.43 ounces
Termination: Flat Top (Tech Cell for Battery Packs)

Suggested charge rate non-peak detecting 70mAh or less, peak detecting 350-700mAh. Slow charging is always recommended.