The Tesla Spider is a compact mod that's very much like a large eGo battery. The 1300mAh cell will last about 13 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 the eGo threading. This gives the device a better look when used with 510 atomizers. To use eGo-threaded atomizers, just remove the beauty ring for a nice uniform look. 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.