This collar is being used on a large dog that had decided that he could stand the shock of the normal collar. He now has new respect for this collar and no longer goes exploring.
After losing our female scottie in a vehicular accident outside our home, we purchased one of the RF-275 as a test and put it on our our male scottie (yes he is above 30 lbs) and have set it on level 2. The RF-275 has worked perfectly for our little boy. The added feature of vibration has really kept him away from the boundary lines. The fact that it is water proof is a great plus as he has found that jumping into the koi pond is great fun. Great product A++
my Australian shepherd is very stubborn, he has figured out how to cross the fence to get out ,but 90% of the time he won't cross back into yard without removing collar.