The Praxis mod is great device with a unique switch, low voltage drop, small size, and a great price.
Without 510 center pin, so your atomizer will connect directly to the positive pole of the battery.
Hybrid connection on the top, when you connect any atty to the mod it gives a hybrid look
Hybrid adapter thread: M20x1
Unique recessed firing switch
Houses single 18650 battery (batteries sold separately)