The Tesla Sidewinder II is a compact mod that's very much like a large eGo battery. The 2000mAh cell will last about 20 hours of constant use. It's variable voltage from 3.3 to 4.8 volts, and is adjusted by turning the knob at the bottom of the device. The connector is 510 and eGo threaded, with an optional and removeable beauty ring that threads on to it's own threading, so you can use eGo threaded atomizers while leaving the beauty ring on. This gives the device a better look when used with 510 and eGo atomizers. The switch is elongated so that it's easier to find and press. Five clicks turns the device on or off, and the light will flash when done correctly. To charge the device, remove the beauty ring, set the voltage to 4.2 volts, and attach to and 420mA eGo charger. Lastly, the finish has a subtle texture to it which makes it very comfortable to hold.