The Impact II has a single white LED. The output is 7 lumens. This light is incredibly bright for such a small flashlight. PT does not state whether the Impact II is regulated. For the low price ($22), logic would dictate that it is not regulated.
LED regulator circuitry ensures that the battery drain is carefully controlled. Regulation is necessary for high drain LEDs. A 1watt LED may have a regulator which ensures that fresh batteries would provide, for example, 12 hours of full output followed by 6-10 hours of diminished output. The Impact II is rated for 75 hours, so regulation isn't a necessity-the light simply burns very brightly for a very long time.
The light is powered by 4 AAA alkaline batteries (included). The lens is a fixed focus. I have never found adjustable focus lenses - as found on the Mag Lite - to have any practical purpose. I always adjust such lights to the tightest beam. The Impact II has a focused beam with slight concentric rings. The rings are useful if you want to use less than full illumination on a reflective object at close range. The Impact II (like similar flashlights from Princeton Tec and Pelican), uses an O Ring for an effective underwater seal.
The output and longevity of this light is nearly unbelievable. The amount of light, and the length of time the batteries last (AAAs are often short-lived) is difficult to convey. It is remarkable to have so much in such a small package.
The light is durable. I have dropped it in a rear pocket and sat on it. The only design flaw is the lens shroud. The shroud only protrudes 1/16" beyond the plastic lens. Placing the light lens down on a surface with grit or on the ground could easily lead to scratching. The shroud should be 1/8" or 1/4" longer. I originally purchased one light as a backup for my headlamp and intended to toss it in my deck bag pocket and leave it. The light is so impressive that I have purchased two more.
The Impact II is available in blue, red, and green, all transparent. The latter two colors are particularly well suited for outdoor use. If the lens shroud were longer, this light would be technically perfect. Highly recommended.