KSD Chi you MOD Main features:
1.both stainless and brass available
2.suitable for 18350/18500/18650 battery.
3.you can screw the button tightly, then the button is locked. You can
also screw all the way up to lock it in case of the unit automactically fire
4.there are 3 air holes in the top part, you can control the air flow
by screwing the top ring
5.laser printed mark is Chi You.
6.as for the function ,no PCB, and there will be no problem even when
you put wrong of positive and negative terminals of the battery.