By the way, I have also tried a catadioptric lens (I had very high expectations on it):
www.mtnelectronics.com
Partly it provides a similar effect as in the Pelican StealthLight: light from LED reflects from the lens' central part and goes back, then the reflected light reflects again from the main reflector - almost the same as if the LED is aligned backwards to reflector.
But the total candlepower was significantly less comparing to a single fresnel lens, that I currently use in the LS-A2M flashlight.
10158 Carclo - 60mm Ultra Narrow Catadioptric
10158 Carclo - 60mm Ultra Narrow Catadioptric

Partly it provides a similar effect as in the Pelican StealthLight: light from LED reflects from the lens' central part and goes back, then the reflected light reflects again from the main reflector - almost the same as if the LED is aligned backwards to reflector.
But the total candlepower was significantly less comparing to a single fresnel lens, that I currently use in the LS-A2M flashlight.