Exceptional protection and organization for big files. Treated to resist the growth of bacteria, mold and mildew that can cause stains, odors and product deterioration. 2 prong "K" style fasteners. Tyvek gusset expand up to 2". Letter size; straight cut tabs. 23 pt. pressboard with blue exterior, manila interior. File Folder Type: Antimicrobial; Size: Letter; Folder Material: 23 pt.