Our Heavy duty Flags are screen printed on 210 denier Nylon Material and come with FOUR rows of stitching down the right hand side (Instead of the usual two rows). They also come with two brass eyelets down the left hand side for attaching to a flag pole. They are over twice as thick as our regular Polyester flags and so therefore last significantly longer when hung on a flagpole. **Although nylon flags are approximately 3 times thicker than regular polyester flags, you would not necessarily get 3 times more use out of a nylon flag than a polyester flag.  In fact, in our experience, its worth buying 2 or 3 x polyester flags instead of 1 x Nylon Flag.**