This season’s hottest toy is a remedy for  Attention Deficit Hyperactivity Disorder (ADHD), anxiety and  autism – or at least that is what it is being marketed as, despite being highly disputed by experts. But regardless its growing popularity, fidget spinners have been banned across several classrooms in the country.

This latest fad among school-going kids was supposed to calm nerves, relieve stress and improve concentration but the new anti-fidget toy is whipping up anger among teachers.

Read: Fidget Spinners: Can They Actually Help You Feel Less Anxious, More Focused?

As  one teacher blogged: “The only thing my students seem to focus on... is the spinner, itself, and not their work. It’s like a friggin’ siren song.”

Several parents along with leading child safety advocacy groups have demanded that fidget spinners be recalled and said it requires a choking hazard warning. The uproar was triggered after a 10-year-old girl in Texas swallowed one of the bearings from her fidget spinner and choked on it. Soon after, many similar incidents were reported, deepening parents' concerns.

"If it is releasing small parts it should be recalled because it doesn't have warnings on the packaging," Nancy Cowles, the executive director of Kids in Danger, told BuzzFeed News.

Any toy marketed toward children has to comply with the Federal Small Parts Regulations, which require manufacturers to put a label on products that pose choking hazards.

Nobody has ever studied the impact of fidget spinners specifically on mental health or cognitive functioning. And the related research isn’t all that promising either.

For example, there is some evidence that encouraging children with ADHD to squirm and move their limbs can help direct their focus rather than making them sit still. But that study looked at kids’ physical activity, not a small spinning device that barely requires any movement. And kids without ADHD didn’t benefit from the extra fidget.

Why is it so addictive?

There have been many such crazes in the past that have relied upon collectibility or competition, but the fidget spinner has gained popularity in such a short time just because its addictive nature. The feeling one gets from holding a fast-spinning contraption is the major part of its appeal. As you tilt it back and forth while it whirrs, you can feel the various spinning forces ripple in your hand.

What do people do with fidget spinners?

Honestly, not much. But many fidget spinner users say the real fun comes from trying to pull off various tricks and stunts with a spinner. As it spins it can be balanced on top of fingers, toes, and if you’re really daring, your nose or forehead. If you have more than one you can stack them on top of one another, and create a spinning tower that plays with your eyes. Perhaps the biggest challenge is throwing a spinner to your friend or trying to catch it, a feat more impressive than pulling off the bottle flips.

How popular is the fidget spinner?

It’s hard to convey just how popular the fidget spinner is. But one figure stands out – 49 of the 50 best-selling toys on Amazon are fidget spinners or their squarish sibling, the fidget cube. 

According to Google trends,  online searches  for fidget spinners began spiking in April.  The inventor  of the device can’t explain the surge in interest (though it may have something to do with the mesmerizing  YouTube videos  of fidget spinner hacks and tricks).