All Onewheel self-balancing electric skateboard models are being recalled due to serious safety concerns, as announced by federal regulators.

Onewheel skateboards are manufactured by California-based Future Motion. As the name suggests, they have a single, self-balancing wheel with a small deck to stand on to either side of it. The successor to toys like hoverboards, they’re surprisingly popular among adults with urban commutes, zipping down bike lanes in crowded cities.

The U.S. Consumer Product Safety Commission (CPSC) revealed that riders risk serious accidents as the boards can stop balancing if certain limits, like downhill speed, are exceeded. If they stop balancing, riders can be thrown off the toy going faster than 20 mph.

The CPSC reported that Future Motion has received numerous incident reports, including four deaths between 2019 and 2021, along with severe injuries such as paralysis, traumatic brain injuries, fractures, and ligament damage. These fatalities were attributed to head trauma, with at least three of the riders not wearing helmets.

Owners of affected Onewheel skateboards are urged to stop using them immediately. The recall covers all Onewheel electric skateboard models sold from January 2014 to September of this year.

To address the safety issue, Future Motion’s Onewheel team will release a safety alert feature called “haptic buzz” through a firmware update for certain board models. Original Onewheel and Onewheel+ boards are not eligible for this update. Riders who don’t qualify for the update can dispose of their boards and receive a prorated refund in the form of $100 in store credit. The hope is that that refund will be enough to convince riders to stop using unsafe models, but it’s a fraction of what they cost. A new Onewheel costs upwards of $2,200.

The Onewheel team emphasized the importance of not using boards that are not updated and the need for helmets and protective gear. The CPSC had previously warned against using these skateboards in November due to safety concerns, and this recall comes after months of delays and resistance by Future Motion.