The BugOut "Cree Q5 Super Premium" module is rated 4.5 Volt to 9 Volt, which means it most probably will not run regulated with a 18650 cell, which gives 3.7 Volt.
The Wolf Eyes drop-ins rated 3.7-6 Volts will, and they work great, have one single step 170 Lumens running either a 18650 or a R123 cell, both works fine.
I am looking for one of these BugOut drop-ins too, but will be using either a 2x18650 or 2xR123 setup with this one from BugOut.
Wolf Eyes also have a 190 Lumens two-stage 3.7-6 Volts drop-in, which looks interesting.