Kryptonite KSS Black Mech Mod is a solid copper mod and comes with 3 tubes for 18650, 18500, and 18350 batteries. It features a direct atty to battery top cap for minimal voltage drop. The KSS comes with a recessed button and a double throw reverse locking brass ring to prevent unwanted firing. The KSS mod has almost no measurable voltage drop and no heat on the button no matter what you build. It is serialized on the inside of the top cap so that you can customize the finish however you want without having to worry about engravings or ruining the markings.
These are very limited production, only about 400 made.