Schwalbe Marathon Tires are puncture resistant, not puncture proof. I had to pull that little piece of a steel belted radial tire from my tire this afternoon. It was my second flat of the day. I could not find a leak in the tube or feel anything in the tire after breakfast. That was only one problem. The other photo shows the hole in my Park frame pump where it should slide over the tube valve. If I had been out away from town this would have been a huge problem. Sac ford, Arizona has a Walmart (my only choice since the bike shop was not open). I would like to have found a better pump.
When the puncture came this afternoon I had to remove the panniers an lay the bike on the ground. It took nearly an hour to find the leak, remove the steel, reinstall the wheel and put everything back to ride again.
The added material probably helps. It isn’t perfect.