Meant to protect more than smartphone data, the $140 Yellow Jacket smartphone cover conceals a stun gun, New York Times reports.

A Times reporter tested the device on himself, and noted that “the shock was really more startling than painful,” although there were small red marks where the electrodes had touched him 24 hours later.

The device also requires preparation, including removing the safety cover from the electrodes (which need to touch skin to be effective) then turn on the switch and press the illuminated blue button. The author suggests that the cover is more of an effective deterrent than defense – the loud buzz and blue arc between the electrodes is intimidating enough.