The Autopilot Buddy for Tesla cars is no friend of yours, the National Highway Traffic Safety Administration said in a cease and desist letter to the product’s maker.

The magnetically attached device clamps onto the wheel of Tesla models with driver-assistance features enabled to fool the car’s Autopilot system into thinking that the driver is actively in control.

The NHTSA statement today said it had directed the firm that sells Autopilot Buddy--listed as Dolder, Falco and Reese Partners on the product’s website--to halt all U.S. marketing, sales, and distribution, and respond by June 29, to certify compliance.

The Tesla Autopilot and Enhanced Autopilot are a set of driver-assistance and self-driving features, only some of which are currently available, but which the company says will be enabled as it obtains regulatory approval. These include automatic lane changing, automatic steering, summoning a car to one’s location, and self-parking.

The Tesla system allows a driver’s hands to be off the wheel for varying durations, depending on speed, task, and other conditions. Autopilot disengages if a driver doesn’t respond to a warning repeated three times to put the hands on the wheel since a September 2016 update.

By simulating the pressure of hands, the Autopilot Buddy, which costs $199, disables many warnings. The product’s site is covered with disclaimers, such as that the product is for use on a track only, and that it’s designed to reduce Autopilot “nagging.”

Tesla has been criticized for releasing assistance features prematurely and for creating an environment in which its owners rely too much on automatic systems. The National Transportation Safety Board cited inattention “due to overreliance on vehicle automation” as one factor in a May 2016 accident in which a Tesla driver was killed after slamming into the side of tractor-trailer, but the truck driver had failed to yield right of way as well.

The NHTSA’s Deputy Administrator, Heidi King, said in the cease-and-desist announcement, “By preventing the safety system from warning the driver to return their hands to the wheel, this product disables an important safeguard, and could put customers and other road users at risk.”

As of Tuesday afternoon, the Autopilot Buddy site now notes that sales are only available to customers outside of the U.S. with the note, “We are not taking orders for U.S.A. residents. We hope to resolve this as quickly as possible.”