No MAP? Seems pricey for PWM box.
There barely more than £30's worth of parts bought individually at retail. Bought en masse in a commercial scenario who knows how ridiculously cheap this box is to make.
Regardless considering previous 2x18650 pot/pwm boxes (such as the HexOhm clones) $60 is a too much for a chinese pwm box especially when chipped boxes such as the Vapor Storm Puma 200W with tank! for $45 ish after MAP why is this $60?

I'd snap it up at $35, maybe $40 but $60 is taking the piss. I'd rather build my own with well known, easily accessable, tried & tested parts:-
using one of Big Al's (numerous) PWM boards. ie:-

using mod makers modmeter v2 lcd readout :-

& 1 of modmakers own boxes:-
My basis theory is that the written word was literally a virus that made spoken word possible. [An aural virus so to speak.] : William S. Burroughs
https://www.youtube.com/watch?v=yqukFWVCt04