Hyperion Transmitter Battery Pack - LiFe 6.6V 2080mAh (5C) - Futaba 4PK ? Weight: 109.2 g ? Dimensions: 78.2 x 41.3 x 16.8 (LxWxH) ? See full datasheet ? Transmitter pack for Futaba 4PK and similar tranmsmiters using 5-cell (6.0V) NiMh flat packs. Almost all transmitter power packs today are made using NiMH cells. Many users have noted the much higher capacity or lighter weight of Lipo cells, but LiPo have voltage "too high" (3.7V/cell) to work reliably with most transmitters, receivers, and servos. But unlike LiPo, LiFePO4 cells (3.3V/cell) can be an excellent replacement for NiMH on voltage basis. And compared to high-capacity NiMH packs, the Hyperion G3 LifePO4 Radio batteries have these other advantages: More capacity per gram, meaning longer transmitter duration between charges Almost no "self discharge", so your radio is always ready to go even weeks after charging. Faster charge time The pack includes Safety PCM circuits to allow charging inside Transmitter, using standard wall NiMH charger. Absolute Max charge rate is 4.8A CAUTION These packs are LiFePO4 chemistry. Only charge them on quality chargers - such as Hyperion EOS line - which have a dedicated charge routine for LifePO4 cells. The only exception is the Transmitter packs with PCM, which may be charged while in the transmitter, using the standard wall charger supplied by the Tx maker. NEVER attempt to charge damaged packs. Read all cautions on product packaging before using these packs.