The Step-It is a plastic snap-on band in two designs: one with a watchlike step-count display (see above), and one that lit up when moving. According to the Consumer Product Safety Commission website, over 70 reports have been filed of skin irritations, burns or blisters.
It's good that McDonald's quickly stopped selling these products last week, but what do you do if you already have one? The CPSC recommends you "immediately take the recalled wristbands from children and return them to any McDonald's for a free replacement toy and either a yogurt tube or bag of apple slices."
The recall affects all the Step-Its delivered in Happy Meals, which amounts to 29 million units in the US and 3.9 million units in Canada. That's a lot of plastic.
I tried one out before they disappeared. It was a terrible fitness tracker. But, yeah, my son liked wearing it.