Yes, the 1s is designed for the 18650 and is regulated. I like my DBS and the build quality is very good. I like that it is upgradable (I have several pills including the MCE) and can change them easily. I like its simplicity, no bells, whistles, or funny bezels or tailcaps. Sure it is plain looking, but it is a work light and I need simple. The DBS is known for being a thrower, however I use it with the MCE OP reflector because I use it at closer ranges. The MCE version isn't quite as bright as some of the other MCEs, but like I said, form is as important as function and a smooth body is important to me. Plus, you get a large choice of LEDs and color tints. Also, the 1SM-2 pill will be regulated if you use 2 18650s (with longer extension)or 2 18500s (with the shorter extension, which I prefer). Its the voltage that makes it regulated and the two batteries are needed to make it regulated. If you don't need multi modes, this is, in my opinion, the best pill, especially for tactical use.