Why are you using "Force-Free" in any of your wording, titles, names and so forth? Did you know the shock collars aren't force-free? That they harm the dogs to the point of them being fearful, shut down and can and have led to aggression directly to people and redirected aggression to other animals/people. The damage these devices go far beyond the physical but to the emotional and mental well being of the animals. Please do not use these people for your dog's training. Dogs have been permanently damaged physically around their necks with burn marks so severe at times they had to be put down. There are scientifically proven Force-Free methods that do not need any aversive tools whatsoever. Please do your research before selecting a trainer for your beloved companion. Always ask these questions when looking for a trainer: What do you do if my dog gets it wrong? What do you do if my dog gets it right? What are your credentials, references? Please do not let anyone who uses these types of tools including choke chains, prong collars, electric fences or anything that will frighten, scare, hurt, intimidate your dog. Look around, ask questions. Find a qualified Force-Free trainer. The Pet Professional Guild has the best resources for Force-Free trainers.