More than 100,000 devices have been distributed since last year that allows Colorado highway drivers to interchangeably use carpool or toll lanes.

These switchable transponders are available through the Colorado Department of Transportation. It gives drivers the option of how to use CDOT’s express lanes on Interstate 25 and U.S. 36.

The transponder is connected to drivers’ ExpressToll accounts. 

“Commuters know how they’re using the road on a daily basis, so there’s no need to stop and to pay a toll," said Carolann Samuels, a spokeswoman for Plenary Roads Denver, which manages express toll lanes.

The Colorado Department of Transportation will soon provide free transponders for drivers who exclusively carpool in express lanes. That’s ahead of a planned move in January that will require at least three people to be inside a vehicle for carpool lane purposes.