Features Made of 2 2600mAh cylindrical 18650 cells with PCB and poly switch for full protection. Light weight and higher energy density than any rechargeable battery. No memory effect and rechargeable. You can build 7.4V/5.2Ah Li-Ion battery pack by connecting two or three PCB ready battery module in parallel. Perfect 7.4V battery pack for bike lighting, RC toy (cars and airplanes), robots, cameras, DVD external battery.