This is the $120 WASP personal defense 9mm handgun accessory. It can be attached to any modern 9mm handgun with threaded barrel and allows a user to fire a single, less lethal 6.5 ounce baton “that hits you like a ton of bricks” before instantly reverting to regular, more-lethal bullets. Some more info while I sit on my hands until they go numb so my fists aren’t such deadly weapons, albeit only briefly:

The WASP can be especially helpful in avoiding accidental shootings and killings.

the WASP less-lethal weapon accessory also has these advantages:

It’s safer for bystanders, and will not travel through walls or downrange.
The WASP transfers more force than a bullet and will not over-penetrate, so it has better stopping power.
It creates no additional risk for the user, since once the WASP is fired, the firearm reverts to a standard, loaded 9mm pistol.

Hey, whatever prevents you from actually shooting a roommate you mistook for an intruder. “You knew it was me.” I swear I didn’t — you didn’t announce yourself! Plus you look so much bigger and scarier in the dark (I knew it was him).

Keep going for a couple more shots and a promo video while I speculate if wasp was really the best name for this product.

Source: Geekologie – Warning Shot: 9mm Handgun Attachment That Fires One Giant Less-Lethal Round Before Regular Fire