I was gifted a first gen JetBeam RRT01 with an astrologers lens attached. Super nice little light and with the red lens attachment it is great for putting out a little bit of light and not getting the retinas that used to dark all upset so night adapted vision remains intact. Need more light? Twist the dial and plenty of light to walk around at night.
I used it for night time photography but also at times play tricks on people raising and lowering the brightness while raising and lowering my arm and twisting the dial without them noticing.