This is the basic ego battery fit with all the ego series ecigarette! Electronic cigarette batteries are power supply devices in an electronic cigarette. Without batteries, atomizers and cartomizers can not be heated. ecigg uk batteries are one of the best quality ecig batteries. Long lifespan. Each battery has a 5 times on/off protection. No more accidental activations. Match with most 510 threading atomizers/cartomizers.