Great Post Adamlau,

I have my Surefire M4 & M6 setup with Lumens HO-M4A, 12V, 550 lumens and a Lumens HO-M6R, 13V, 700 lumens respectively.

The higher voltages allow for the use of rechargeable CR123A batteries in the flashlights. They work great! Very bright light that has a run time of about 35 minutes with this setup.