The EHPro Crystal Mod is the perfect mod to break into mechanical mods! The Crystal is very simple, yet very well-made! It has a recessed button that won't fire under it's own weight. The negative contact is made of solid brass, and the positive pin is pure copper for excellent conductivity and low voltage drop. The top pin is floating to ensure any atomizer will fit flush, while the other end of the contact has an additional screw to adjust for variations in battery size. The Crystal only accepts 18650 IMR batteries, and works best with the flat-top variety. Each unit will come with a nice engraving and unique serial number. The EHPro Crystal is the most economical way to get your hands on a well-made and hard-hitting mechanical that can fire anything you throw at it!