The Yellow Jacket smartphone case is meant to protect more than a phone.

The $140 smartphone cover conceals a stun gun.

Stun guns, of course, have been the subject of some controversy. There have been reports of deaths caused by some of these devices, and film and TV depictions often show people crumpling in a writhing mass when stunned.

After reviewing the specifications of the Yellow Jacket with Steve Tuttle, spokesman for Taser International, the leading maker of stun guns, I was convinced that this case wouldn’t pack a huge punch. According to the spec sheet, the stun gun has an output of 650,000 volts at 0.8 milliamps, which the company said should be painful, but not harmful.

So I tried the Yellow Jacket on myself. I zapped myself on the inside of my forearm, which Mr. Tuttle had suggested because it has relatively few nerve endings. There was a stinging sensation and I felt an electrical shock travel to my wrist. The shock was really more startling than painful. It was no worse than when I have mistakenly bumped into an electric horse fence, or when as a child someone persuaded me to test a 9-volt battery by touching it to my tongue. Twenty-four hours after I zapped myself, there were small red marks where the electrodes had touched me.