Hi Kathy! This is my "opposite lead" reminder band. Many times there are so many turns and lead changes when filming that it gets a bit confusing cueing everything on the opposite lead (on video when I say "right lead" to you it is actually my left side). Having the band on my left wrist helps me instantly know that this is my "video right lead".
While I don't really need to wear this anymore, I have grown attached to it and feel empty "armed" without it now. So now I view it as my good luck charm .