I use home again chips. Make sure the frequency you get is a universal one so any chip reader will read it. And make sure to REGISTER IT!!! Chips do no good if they aren’t registered. You’d think that’d be common sense but hey... And typically once you register it, it’s good forever. Some companies have a yearly thing you can sign up for where they’ll send flyers out to local vets and shelters in the area. Hope that’s helpful for ya!!