I always wondered about the compatibility of threads/parts between SF and other US-brands such as Pelican, Streamlight, and Pentagonlight. I think I asked once and was ignored. Right now I have a Streamlight Scorpion LED head on a Vital Gear FB1 body. This means the threads match perfectly also between the Scorpion and any E-series body!...but it won't work because the E-series body won't go far enough in the Scorpion head to make contact, but at least it fits. I wonder what other things fit. I'm surprised those with various SFs, SLs, PLs, and Pelicans don't get the itch to swap things around just to see. Hopefully someone will.