The F13 I am selling has been worked over pretty well. It includes the stock lanyard, 18650 adapter, and AAA adapter.
The driver was replaced by one of Wight’s designs. This one https://budgetlightforum.com/t/-/26993 Driver
It is setup with 14x 7135’s for a total of 4900mAh. I measured 4.65 amps with my harbor freight dmm and Samsung 15M’s.
STAR offtime is used, w/ Moon - 4% - 20% - 50% - 100%.
Both springs are copper braided. 22 gauge wire used for emitter.
LED was replaced with an XML2 U2 1C on a Sinkpad.
Emitter insulation ring was replaced with a very thin one from fasttech. The stock one blocks a lot of light. I measured a 10%+ gain by changing the centering ring.
The bezel was also filed down to keep pressure on the insulation ring that was much thinner.
The light is now more than twice as bright as stock according to my non calibrated ceiling bounce 
Looking for $30 shipped CONUS. Not looking to ship outside the US at this time.
ALSO
TR-J18.
Copper braided springs and a resistor mod to bring up the current. On two KK ICR’s, it pulls ~10 amps on high. Maybe 70 watts with voltage drop?
That would be about 10 watts per XML, minus any driver losses.
Includes a belt holster and 2x 18650 adapters.
$40 shipped CONUS OBO.