In the United States Postal Service (USPS) system, is part of a series of "Unique ZIP Codes."
: These items feature a zip fly closure and a roomy fit through the seat and thigh.
: Most versions are made from a cotton-elastane blend for stretch, though 100% cotton "non-stretch" versions also exist. 3. Biological & Genetic Research (DUF569)
In scientific literature, often refers to the DUF569 gene (Domain of Unknown Function 569). 569™ Loose Straight Zip Fly Jeans For Men | Levi's® US
: These are typically assigned to specific large entities, such as government agencies, universities, or major corporations that handle their own final mail delivery.