A tuning company in Roseville, California will pay $1 million in fines and penalties after it pleaded guilty to selling thousands of products that allowed pickup truck owners to bypass the emissions control systems of their vehicles.

Two weeks ago, Sinister Manufacturing Co was charged for selling tens of thousands of “delete kits” for trucks and accompanying tunes that allowed trucks to run normally once the emission controls systems had been removed. The company pleaded guilty to conspiracy to violate the federal Clean Air Act and defraud the United States as well as violating the act by tampering with the emissions control systems of diesel trucks. It will pay a $500,000 criminal fine and $500,000 in civil penalties. In addition, Sinister has been prohibited from making or selling these devices and must destroy any it still has.

“Sinister Diesel sold products that allowed drivers to strip the emissions controls from their trucks, causing a dramatic increase in the release of pollutants that worsen air quality and harm the quality of life,” U.S. Attorney Phil Talbert said. “Environmental laws that control diesel pollution are especially important to protect sensitive populations such as the young, the elderly, and people who suffer from respiratory conditions. My office will continue to vigorously prosecute those who place profit above the public’s health and the environment.”

Watch: Texas Ford Truck Driver Rolling Coal On Cyclist Gets Blowback Of His Own

Talbert’s office told The Sacramento Bee that one-quarter of Sinister’s gross revenues came from the delete products it offered. In addition, it revealed that between October 30, 2015 and July 17, 2017, it sold 39,792 defeat kits for trucks, including at least 35,960 kits that disabled a truck’s exhaust gas recirculation systems. Court documents added that the tuner advised customers to remove its delete products to pass emissions tests and then provided instructions on how to reinstall them.

“At times, Sinister characterized its delete products as for racing and/or included disclaimers in its sales and marketing materials indicating that its products should be used only in off-road settings,” the documents added. “However, Sinister knew the bulk of its end-user customers were diesel truck drivers who used the delete products they purchased from Sinister on public roads, not racetracks.”

 Californian Tuner Fined $1M For Selling Diesel Emissions Cheat Devices For Pickups