I LOVE the Cardio Canine!  I often walk and run with our two Golden Retrievers.  One is 80 pounds and the other a very energetic 50 pounds.  In the past, our runs or walks would sometimes get cut short because they would wear me out by their pulling (yes, this is probably indicative of poor obedience training but hey....).  At any rate, I can't believe the different the two-dog system made.  We ran 2-miles and could have keep going.  They were happy, I was happy!  When they invariably pulled, it pulled from my waist rather than off-centering me from the shoulder.  I was able to RUN with good form, arms could swing freely - unbelieveable.  Walks were even better...relaxed, plenty of lead but enough to keep control, water bottle is perfect, treat and bag pouch perfect.  Not only is the engineering of the product excellent, the quality of the product is unsurpassed.  I have spent some time rock-climbing and the belt is similar to a climbing harness.  Very secure.  This is heavy-duty - your dog will not unclip and extremely comfortable (make sure you order the right size - I did with no problem).  This will not fall apart on you - probably ever!  I know this is starting to sound like a paid sales pitch - I can assure you, it is not.  I can only say fantastic things about this product - I will use it every time I walk or run with them.  When I can - I'll even send you pictures.  Thank you very much!!