What is that on the Ref's hand?

[Tickle_Me_Elmo]

My GF has noticed a bracelet/strap on NFL Ref's hands, and has questioned me many times what it is. Not really knowing, but taking a educated guess, I suggested that it was what they used to keep track of downs, looping it over their fingers. She finds that answer completely absurd, stating, "How hard can it be to count to 4!". Sticking to my answer, I stated that when you have as many things going on that you need to keep track of and pay attention, it's pretty easy to forget (I pitched for 6 years within a MLB system, so I understand how easy it is to lose track of outs, counts and what not).

Then she noticed that she has never seen a Ref throw a flag, she just notices one on the ground. So now this "down counter" as I call it, has now become a Penalty Flag Slingshot, lol.

So I come here today to ask of you all, what is it? I could be wrong, wouldn't surprise me if I was, but I'm guessing it is not a Slingshot



This Photo didn't help my case since the loop is now off of the fingers