The Aleph 19 head Cree XR-E LE has a fully-regulated GDuP Microprocessor based boost/buck driver with a Cree "Q4" LED. It will run on a single cell CR123, R123, 3.7V Li-ion battery.
The GDuP will run 3 brightness levels with a McClicky switch.
Click through the 3 levels and release after the blip to set. The GDuP turns your single stage light into a three stage clicky or twisty. Has the capability of retaining your last entered state. Labor charge incurred in production run.
Over 3 months of labor went into creating this converter. This is the A19 head without the UV engraving.