I bought two UltraFire WF-606A Cree Q5-WC 1-Mode from Fasttech. The pill unscrews and uses the same thread pitch as a P60 dropin at the pill-reflector junction. So looking to up the power a little I used a XP-G 0.8v-4.5v SolarForce dropin. Remove the pill spring and lathed down the diameter below the threads and the pill fits. If you make your own dropins just make one upside down and the pill should fit without any more modifications. The deeper upside down pill version will clear the reflector and lock into the host a bit better. Those of use that want the two-aa host this is as close as I’ve seen.