I made my own from old spokes. Worth 1000x their weight in gold! Gotten 1 flat in the last 9000 miles of riding. That one flat was from 2 pieces of glass that worked their way through over the course of a week (I remember running over them and wiped my tyres). It was a new tyre and I hadn't reset/re-curved the tyre-saver to fit the profile closely. You can also count on zero flats from goat-heads as well. Next to using proper inflation to prevent pinched-flats, they're the most effective solution to puncture flats.