In case anyone's interested, the Streamlight Scorpion body fits into the tail of the Huntlight FT-01 perfectly. The Scorpion body fits a 17670 cell easily, but can be bored to fit an 18650 also, so you can run your FT-01 on 2x Li-Ions for hopefully much more runtime (if it's a buck regulator, runtime will increase with higher voltage). Also, because the Scorpion has a momentary clicky, this also turns the FT-01 into a momentary LED, which is a nice feature. Anyways, here's some pics.