I ran into this product first on Shark Tank on TV and thought that was an amazing idea.  I hate it when my collar's get a mind of their own and start curling up.  These things are great super easy to put in and clip the magnet to.  Just remember to take them out every night.  I thought the price was a little steep but if you consider price per use and I use them every day then I suppose that the price is justified.  I have had 3 of my friends buy these and a bunch more are interested, great product just wonder how I lived without them ever!