The Active Denial System
Another non-lethal weapon developed to help disperse crowds, the Active Denial System transmits an invisible electromagnetic radiation beam that creates a burning sensation on people’s skin—sending them running. Called the “goodbye effect” by senior military officials and a “heat ray” by scientists, the Active Denial System can heat up water molecules on a person’s skin to 130 degrees Fahrenheit from a distance of 500 yards. Controversial in some circles and dubbed a form of torture by some people, the Active Denial System has proven extremely effective. Security experts expect that the system will eventually be used alongside other non-lethal crowd control methods such as tear gas, water cannons and rubber bullets.
That "grenade launcher" in the pic is a Glock 17C pistol in caliber 9mm.