Heavy-duty poly envelopes resist tears, repel moisture and are available in bright translucent colors for easy organization. Gusset expands up to one and a quarter inches to accommodate bulkier materials. Heavy-duty string and button closure is designed for everyday use. Acid-free, PVC-free and archival-quality. Horizontal orientation. Envelope Size: 11 5/8 x 9 3/4; Envelope/Mailer Type: Expanding Pocket; Closure: String and Button; Seam Type: Traditional.