The Kamry K100 is a fully mechanical 510 threaded mod that works with most 510 threaded atomizers and cartomizers (including Vision Ego and Evod). The mechanical switch assembly is located at the base of the device, with a collar that can be screwed down to lock the switch and prevent accidental activation. The tube also has multiple vent holes for added protection. Ensure that the telescopic tube is fastened just far enough to let the power button activate the atomizer. If the telescopic tube is pulled further, it could push down the button spring and prevent the device from turning into "off" mode. When your ecig is always turned on, it could cause the battery to overheat. Note: Compatible with 18350, 18500, 18650, button top and flat top batteries.