What is a switch? The increasingly popular device can turn a pistol into a fully automatic weapon.

• A "switch" is a small, cheap device that can modify a pistol into an automatic weapon.
• Officials said switches are becoming more common, especially among teens.

What is a switch? No, not the Nintendo — this device is much deadlier.

Law enforcement officials across the country are raising concerns about the devices, also called auto sears. They are small, cheap add-ons that can turn a pistol into an automatic weapon, The New York Times reported.

The devices are turning already deadly weapons into essentially machine guns, further fueling the American gun violence epidemic and worsening outcomes for shooting victims, medical workers and police told the Times.

"This is almost like the gun version of the fentanyl crisis," Kansas City, Missouri's Mayor Quinton Lucas told the Times.

The deadly and illegal device is about an inch in size, and it can easily be made on a 3D printer, much like so-called ghost guns. They sell from $20 to $200 and are increasingly popular among teenagers, the Times reported.

In Las Vegas, 14-year-old Caison Robinson said teens call switches "buttons," noting they have become a sort of status symbol, the Times reported. Robinson was the victim of a drive-by shooting in May, during which police said the gunman used a pistol rigged with a switch.

"It's become a thing you get to be cool," Robinson told the Times. "It's like a trend now."

Federal officials inquired whether Glock — a company known for its 9 mm handguns — could tweak its design to make it harder to attach switches. But the pistol's design, the company told law enforcement and the Times, can't be modified in that manner. Glock did not immediately respond to Insider's request for comment.

Switches join other modifying devices that have made the fight against gun violence more difficult in the United States. Bump stocks garnered national attention and a federal ban after they were used in the 2017 Las Vegas slaughter that killed nearly 60 people. That ban was appealed and then struck down by a federal judge in April.

Despite the uphill gun control battles, the effect of switches can't be understated, officials say. The Bureau of Alcohol, Tobacco, Firearms and Explosives classifies switches as machine guns under federal law.

"The gang wars and street fighting that used to be with knives, and then pistols, is now to a great extent being waged with automatic weapons," Andrew M. Luger, the US attorney for Minnesota, told the Times.