So the mod is a SS 4nine clone from fasttech (
https://www.fasttech.com/p/1772708)
The 4nine uses a hybrid connector. I had no clue what it meant so I hope now that I've understood this simple breakdown will help someone in the future. Basically, the atty makes a direct connection to the top of the battery versus a 510 threaded connector that essentially is a bridge between the atty and the battery.
Pros of the hybrid-
No losses, so less voltage drop
Lowers height of mod compared to 510 mech mods
Cons-
No adjustability so battery might work, might not
Atty needs to have an adjustable centre pin to make a connection
On my particular mod, only my magma RDA works cause it has an adjustable pin. First few hits were super and I was over the moon. But my battery was draining super fast. Realised later, the coil I had wound actually metered 3ohms which is basically unusable on a mech mod. Don't know how that happened but anyway a proper 1.8 ohm coil worked superbly thereafter.
Problem 2- I exchanged the Samsung I bought off eBay for one of Ron's batteries and, whoops, there goes the connection. The new battery was maybe a hair shorter but that was enough to not make connection.
End story, the 4nine only works with certain batteries but if you've got a couple lying around it won't be a problem.
For me the draw was simple, it is absolutely tiny and I haven't even tried 18350 mode yet. And the button has no locking ring that can get stuck and give you migraines.
All in all as an experiment into mechs, I like it. Though I might sell it cause I've learnt I like regulated box mods better.