Any one tried Safe Bandz for child’s safety?

Hi mummies and daddies, I came across this interesting item SAFE BANDZ which can be worn by children, adults and even pets. It has a QR CODE which contain the parents’ or guardian’s name and contact should the person wearing it is lost. I think it’s a good idea. Would like to ask what preventive measures you all have in case a child is accidentally separated from you among the crowd?