This particular item was designed by a woman for women. So what does that mean? It means that the Hummingbird is extremely comfortable and, even when it vibrates and moves around, it makes complete contact with all those erotic areas that women have. The high powered battery unit packs a punch and is sure to leave you breathless. The battery pack is also dual controlled for easier functioning. And it has a belt clip so its closer to your hand. All of this makes for extensive vibration of clitoral, vaginal and anal areas. Requires 3 AA batteries (not included).