The Fi Mini Fastener allows you to securely attach your Fi Mini tracker to any collar with a width up to 2" wide using our J-Clip options. Our Standard clip is designed to attach the Fi Mini Fastener to any collar up to a half inch in width. The Clip screws on with two 6mm hex head screws into solid brass inserts in the clip for incredible strength. The body of the Fi Fastener is made from our favorite TPU soft plastic blend that allows you to pop the fi Mini in and out with ease. Note that we have designed the body however so the unit can be charged in the fastener for convenience. As with all our product the Fi Mini Fastener is warrantied for life and manufactured in America!!!