Voltage
Most stun guns claim pretty high voltage ranges. The Vipertek VTS-989, for example, lists its voltage as 58 billion. Because stun gun voltage isn’t regulated, that may or may not be an exaggeration.
Batteries
Some stun guns come with rechargeable batteries. Others, like TASER devices, come with batteries you’ll have to replace. Rechargeable batteries tend to be less expensive but will charge less over time.
If your stun gun has rechargeable batteries, refer to your manual for how often to recharge it. Many stun guns will need to be charged for one to two hours every month.
Size
Stun guns come in all shapes and sizes: some will be lipstick-shaped and fit in your purse; others, like TASER guns, will have to be holstered. Consider what size and shape will work best with your lifestyle. If you work nights and get home late, a flashlight-style stun gun may be better. If you’re a delivery person looking for an added sense of security, a TASER-style weapon might be better.