A compact 11.1V Li-Po battery with its 3-cell in one block construction, allows this battery to fit inside. Despite its small size it still packs 1500mAh. It comes in a handy storage box.
  
The biggest reasons to use a Li-Po is its smaller size and better power efficiency. Most Li-Po batteries are about the same size as a mini-type battery and is equal in power to a large type NiMH battery. No need for battery slings, battery boxes, or big batteries strapped on to guns. Li-Po is a power source for small carbines, PDW's, SMG's, etc. that doesn't require you to spoil the look of the gun, or run the risk of running out of power in the middle of a battle.
Unlike traditional batteries, Li-Po gives a stable Rate of Fire, Through-out its use. Also, it is not necessary to discharge Li-Po batteries before charging them, allowing the battery to be charged in-between games.
   
Battery specs:

• Configuration: one block.
• Voltage: 11.1V.
• Capacity: 1500mAh.
• 20C continuous discharge rate of 26 amps with 32.5 amp bursts.
• Comes with align balance connector.
• This pack is ideal for M130 to M160 upgrades.
• Replaces a 10.8V to 12V NiMH pack.
• Ultra-advanced Li-Po battery technology.
• 180mm x 20mm x 17,30mm.