While the backpack was admittedly stuffed to the brim there was no sign that the zippers were under pressure or would give from the strain that I could see. My only wish would be for these to have a bass and treble control. When I contacted them they said I could return them no problem. Stufe des ANC ist dagegen schon deutlich besser und eignet sich für das Sitzen im Zug, Flugzeug und wo es noch laute Motorengeräusch gibt. These arrived today. I modded it using a hair dryer by changing the angle it curls. It also holds the device at a great angle so it?s easy to read and input information. THESE "QUINCY" BOOTS ARE SO COMFORTABLE. They are so beautiful and elegant! Control is spot-on.