The JETBeam RRT-0 Variable Output is personally one of my favorite lights. That is not an endorsement I give out frequently.
This particular model of the RRT-0 has a variable output ring, allowing you to choose your desired level of output. Using the ring you can go from 0 to 255 lumens and anywhere in between. The variable output ring means you will never be without the perfect brightness setting, but that isn’t the only thing I love about this light. The RRT-0 is capable of using either one CR123 or AA battery using the optional adapter ring. Having the ability to choose which battery you want to use is a huge advantage. While CR123 batteries give great run time, they can be expensive if you use your light frequently. Using the common AA cell makes it painless to replace your battery when the time comes.
The sum of all parts makes the RRT-0 one of the most versatile and useful lights on the market. When it’s time to buy a new light, this is definitely one to be considered.