Police around the country are starting to use a $200 device to crack down on vehicle window tint violators. In cities like Aurora, Ill., police use light transmittance meters to measure the amount of light that comes through after-market window tints, and if the window is too dark, the driver is issued a fine, the Daily Herald reported.

Most states have had regulations in place for years limiting the amount of tint allowed on the front windows of a vehicle, but the availability and lowering cost of technology is allowing police to concentrate on enforcing such regulations more aggressively. In Aurora, police issued 291 citations for illegal window tint during the first five months of this year, whereas last year, officers only issued two citations during the first five months.

Police cite officer safety as one of the primary reasons for disallowing dark window tint. Several years ago in La Grange, Ill., a police officer was shot with a shotgun after doing a routine traffic stop on a vehicle with dark tinted front windows.

“We’re finding a high majority of the people who have applied the additional tint, gone to the extreme darkness on it, are people who don’t want to be seen or recognized by police,” Aurora Police Lt. Nick Coronado said.

Customized car enthusiasts are also known to illegally tint windows for aesthetic reasons, but police say the regulations are for the safety of drivers as well. Dark window tint can decrease a driver’s ability to see other vehicles or objects, especially at night, which can cause traffic collisions, said Sgt. Ed Ferguson of the Broken Arrow Police in Oklahoma, reported KRMG.com.

Like Aurora, police in Broken Arrow plan to begin actively enforcing window tint laws with light transmittance meters on Nov. 1.

While some drivers dislike the new practice, police in Aurora plan to hold events in which drivers can have their window tint tested for free and avoid risking a $120 ticket.