The products were sold in stores, including Best Buy, Dick’s Sporting Goods, and Johnson Fitness & Wellness, and online on Amazon and the BowFlex website for between $200 and $800. The weights have been in stores since 2004. Consumers are encouraged to stop using them immediately and return them for a refund.

Johnson Health Tech Trading recalled about 3,844,200 units of its BowFlex Adjustable Dumbbells that were sold across the US by retailers including Amazon, Best Buy, Costco and DICK’s Sporting Goods.

More than 300 reports of the weight plates becoming dislodged have been filed, with more than 100 of those cases resulting in injuries, the U.S. Consumer Product Safety Commission said.