This is the "short" version of the S2+ host, made for 16340 & 18350 cells, or CR123A primaries with a boost driver.
This host has nice anodizing and great smooth threads. The OP reflector produces a nice smooth beam with a diffuse hotspot. For a single LED build, just add a 16mm MCPCB with LED, 17mm driver, a bit of solder, and you'll be in business!
To build a triple LED flashlight, you will need to add the following components:
The included driver retaining ring for the pill needs to be modified to work with many of the 7135 based drivers such as the qlite. You can make it work by enlarging the inside diameter of the ring. Instead, I usually choose to solder the driver directly to the brass pill. The single sided 7135 drivers, such as the AK-101-A and AK-47A will work with the retaining ring.
Add an AR lens for an up to 5-10% gain in "out the front" lumens.