City outdoor brand exposure is easily constrained by weather conditions. Many brands engage in street promotions, preparing portable promotional items or event-related giveaways, and can only hope for stable, good weather. When faced with rain and the humid, variable environment, promotional gifts made of paper, cotton, and common fabrics are prone to damage. Once the printed patterns and brand logos come into contact with moisture, they can smear, wear, or become deformed, leaving the brand's visual identity obscure after a rainfall. For this reason, more brands are gradually abandoning traditional outdoor giveaways in favor of custom nylon bags as their main promotional items. The waterproof fabric provides this portable item with strong environmental adaptability; rain and humidity pose no threat, and it withstands daily wear and tear. The printed brand visuals, design details, and exclusive symbols can remain clear and intact for a long time, freeing brand exposure from seasonal and weather constraints, achieving stable offline visibility, and becoming a highly utilized practical souvenir.