im not even sure sos was available back when I got them. I was leary because they seem costly for what they are but have to say saved me from losing my keys and I think my phone once for like a total of half a dozen times. Finding them quickly and with less stress. worth it. once was at a grocery store and the keys that had fell out were to far to hear but an employee started bringing them to the customer service desk when the xmass music started to play from it.