This TT 25 collar is a replacement collar for my mini TT15 dog collar that would no longer power up. I thought it was the battery and got a replacement battery from gun dog supply and found out that the battery was not the problem. It turns out that the TT mini 15 is discontinued so I called gun dog supply and spoke with Dave in customer service and he answered all my questions. I was a little worried that the collar would be too big and after checking my French Brittany's neck size I ordered the collar on line on a Monday and it was shipped the same day. I live in Northeastern Minnesota and I had the collar by Thursday. Even after a shipping delay in Missouri due to bad weather! The collar fit my dog perfectly! The actual unit is a little larger then the mini 15 and the antenna is longer but it still fit's my dog's neck fine and is not to big for her. The actual antenna wraps around her and is out of her way and doesn't hit the trees and shrubs like the shorter antenna did in the past. If I had to I could purchase the shorter flex band but at this point I don't see the need. I sent the batteries back and the very next day after Gun Dog Supply received them I was notified by email that I was getting a credit back on my credit card. Thanks Kathleen for re-sending the replacement batteries for the original batteries that were lost in transit! As mentioned I live in Northeastern Minnesota on the edge of a wilderness and 40 miles from town and have had the Garmin Alpha 100 and TT mini 15 now for almost 6 years and use them almost every day either being outside working, hiking or hunting grouse in the fall. The peace of mind knowing where my dog is at all times you can not put a price on! I did send the TT mini 15 back to Garmin and they refurbished the unit so now I have a back up.