These are LiFe (Lithium Iron) batteries, which have similar properties to LiPo but without the volatility. The Tenergy charger that we sell here will charge these--just make sure it's on the "LiFe" setting. Fits in most crane stocks, M4 foregrips (tested), full stocks, some MP5s, and lots of other places.
Measurements: row 1: 18x20x135mm, row 2: 18x20x67mm
