I was hesitant to try your product but my current leash was causing problems with me and my dog, Cassie.  I have been running for over 30 years and I intentionally bought a Border Collie to run with me.  They don't waste time sniffing - they just run!  I liked to give Cassie the freedom to run with a retractable leash and she is quite bright about not getting caught by a light pole.  It would be difficult at corners because she would be ahead of me and she would reach the street before me, putting her in danger.  Retracting the leash at every corner is a real strain on me.  She is very good at running on my right, staying away from people passing on my left.  One time, I paused for some reason and she thought I was turning left and ran ahead of me right into another fast runner.  He was not happy!  That was the last straw to push me into trying your product.  Cassie caught on very quickly that the circumstances had changed and didn't seem to mind at all running right next to me.  She is at my side at street corners, the leash is right there if I need to keep her especially close to me.  I don't need to use the choke collar anymore.  Best of all, she cannot bother other people.  Dogs seem happiest when their masters are happiest.  Works for me!