The makers of window films are asking for an exemption from federal standards so they can sell a darker film than usually is allowed.

In a Federal Register notice Thursday, the Federal Motor Carrier Safety Administration asks for comments on the exemption sought by the International Window Film Association.

The current standard allows windows to be tinted as long as they do not restrict light to less than 70% of normal. This applies to windshields and windows to the right and left of the driver.

The Film group wants the standard to be set at 50%. It says trucking customers have had difficulty getting the 70% film, and that the darker tint will reduce eye strain and help keep the cab cool.

Comments are due by February 24.