This is a Li-Poly 1600Mah 11.1 volt transmitter battery and charger kit. It fits the Futaba 3PK,KO Propo Helios and JR Propo Z1 transmitters (will need two small plastic ridges removed from battery area to fit in the 3PK). These light weight packs are only 120 grams compared to 235 grams of an 8 cell AA pack. This reduces the weight of your transmitter considerably and lasts a good 7 to 8 hours of run time! Included in this kit is a very user friendly LiPoly 3 cell peak charger. This simple to use charger just plugs into the wall and shows red light while charging and green light when it done. It takes about 2 hours to fully charge a discharged pack. All packs are assembled in house to assure the best quality.