Garmin TT 10 dog collar. This is one of the original collars designed to work with the Garmin Alpha 100 handheld unit. It is a larger long range unit designed best for larger dogs. Have not used it for several years as I purchased the smaller collar for my small pointing French Brittney. Worked flawlessly when I checked it the last time. If it fails to work with your Garmin Alpha, return it and I will refund your money.