ET-300 Mini Educator 1/2 Mile Remote Dog Trainer Total length 20.5” Smallest collar EUC Printfresh Unicorn Garden pajama Set Sz Smallest is ridiculously small (see picture) Largest neck size 16-17” depending on thickness of fur as you want the prongs to be against the neck muscle but not too tight. Gently used and worked amazing along with professional training. Fit Standard Poodle at 40 lbs with plenty of growing room. He’s well-trained and no longer necessary after consistent use in different training exercises. Retailed $200. Has training company logo. Please see all photos as part of description. Smoke free, service dog friendly home. Ships next day!