I want to say these go back to the early Fasttech days but may be wrong on that.
Regardless do remember them and this is why people should not “FooFoo” older flashlights, some were built like a Brick Sheethouse.
Personally like the big threaded pill vs integrated shelf as it gives more flexibility to thicker mpcb boards and lens thickness without a problem.
It is the little brother to the L2 like here;
Comparable version of L2 is the K-08.
Convoy also made a dual 26650 version of that L1 model under the Lustefire brand (I know what a great name)
Think I may still have one of those in the basement MIB, will look later this week.
Edit; just looked and it is model Lustefire U2-D01.