Product review (3 stars): I did it myself with cheap local parts. Consider doing so too; here's how.
I read many of the reviews for this product and examined it closely, as well as watching a 4-minute YouTube video on how to replace/install it. My thought was that there was little reason to pay this much for a piece of string. So here is my advice if you're willing to save time and money, even if the solution is not 100% perfect: Go to your favorite DIY store, buy some 40 pound nylon line and a 4-pack of S-hooks. Make your own replacement strings, keeping the existing pulleys, and install it yourself. It took me under 30 minutes and cost $5. While there is a slight "hitch" in the door opening now due to the S-hooks needing to ride up on the hinge each time, it works very well and I always know how to fix it again in the future for $0. Also the metal S-hooks will not break as the former nylon string ends did. Your mileage may vary.