The BH-209's variable mag-bottle aperture allows for full control of beam width, which can be dialed from a relatively narrow 1cm setting to a splashy 10:6 expanding cone (6-meter beam diameter at a range of 10 meters) useful for crowd control.Powered by a Striggs & Bratton 2-stroke microfusion plant, the BH-209 need never be recharged, provided it is allowed to "breathe" periodically. When primed and flipped from "safe" to "decidedly unsafe," the BH-209 cycles local atmospheric gases into the plant, producing a noticeable acoustic effect. While this hum is stealth-defeating, many law-enforcement agents have reported that it serves as an excellent deterrent.