I originally purchased the Cardio Canine hands free system when I acquired a bouncy boxer/bulldog mix shortly after having shoulder surgery.  This 85 pound monster was a shelter dog without much in the way of leash manners.  I love the strength and sturdy construction compared to other hands free leash products.  I am also a runner, so I was looking to invest in something I would use long term after my rehab.  The Cardio Canine has been the best pet related purchase I've made in a long time.  I now run with my big guy, Malone, by my side, and have added the second leash for his sister, Zoe!  If only it would tire them out!