I purchased these resistance bands after going through PT for my right shoulder which was diagnosed with tendinitis. The PT gave me both stretches and band exercises to do, and these bands have really made all the difference. I was given a few of those flat elastic bands by the PT, but they quickly gave out, while the Black Mountain Bands have lasted a full year of use 2-3 times a week. Using these bands has brought my shoulder from being painful to move without any external load to being able to do pull-ups, rock climb, and play squash completely pain free. The handles are comfortable and make it easier to pull with more force, and the door jam strap gives me confidence that the bands won't come loose. The bands do show some wear in the middle where they come in contact with the door jam, but it's not surprising given the friction and I'm counting on the lifetime warranty in case it does break.