From the United States Consumer Product Safety Commission:
This recall only involves the Fitbit Ionic Smartwatch. It was sold with a polyurethane band and has a 1.4-inch color LCD screen. The watches were sold in slate blue/burnt orange, charcoal/smoke gray, blue gray/silver gray, and a special edition co-branded with Adidas in ink blue/silver gray. The smartwatch tracks activity, heart rate, and sleep. Only the following models and colors are included in this recall. For the Ionic device, the model number (FB503) is on the back of the device near where the band attaches. Fitbit is printed on the front of the Ionic Smartwatch.
For more information, please visit Fitbits recall page at help.fitbit.com/ionic.