Ideally suited for outdoor applications that require high durability. If long life and flyability are important to you as well as economy, then this is the ideal woven flag for you. Like other polyester flags, it is hydrophobic meaning it repels water. Polyester is the superior fabric choice for all your flag, banner and pennant string needs.. For outdoor display, our flags are made of 100% heavyweight polyester, specially treated to reduce sun and chemical deterioration, and are finished with strong headings. Outdoor national flags are devided into two groups called banner flags and outdoor display flags. Outdoor display flags are flown on flagpoles. Banner flags are vertical pulldowns used as decorative flags.