It looks like it's limited to being useful only to those who like to trigger-fire their mod. That could be deceptive though, but without actually getting to feel the ergonomics of it in hand, I can only guess that that's the case.
If that actually were to hold true though, that's strike one in my book.It's really more of a novelty item in my opinion.. So I doubt the folks that this is geared towards would care.
As for ways to improve it, there's one thing that's been nagging at me. And that's the "rubber" that's being referenced. Now if that's in regards to a silicone sleeve for the mod itself, that's great. But if the sleeve (18650 adapter) is rubber, I think at best, that's only a recipe for annoying the user, as rubber doesn't slide easily. Especially when butted up against another plastic, such as the sleeves on most batteries. At worst, the rubber sticks to, and tears the protective sleeve on the battery.
Either way, a very poor choice on someone's part.
I'm also curious why there's a Chrome finished one shown (in the 4th picture on your site, beside the matte black version) but not available for sale?
(It's not listed in the drop-down menu for "color choices)