dog training collar 800M remote rechargeable and waterproof dog trainer alone collar

I am very happy with these collars, I have 3 sisters dogs almost 2 yrs old. They copy each other with barking and some aggression when they see other dogs and become a pack.Easy to understand how to use them. I don't have to use them a lot but when I do the dogs automatically respond to the buzz or vibration and stop doing what they shouldn't be doing .Even if I'm up stairs doing jobs I take the hand control with me and if I can hear them barking at the back gate ,a quick push on the controller and they stop. They don't seem to know where this is coming from, and no not think it's coming from me which is funny. I only have them set on the lowest number 1 and it still works.Jacque