Forgive me if this is answered somewhere, but I just can't find it. How secure are the Magicbands as far as staying on the wrist? I am mostly concerned about my 5 year old. I'm afraid he will mess with it and it will come off. He may leave it alone if we stress that it is important not to lose it, but then again he might not. I saw something on Etsy called a bitbelt to help secure them on. Anyone use one or something like it? Is it necessary? Thanks!