Adams® 3-Up 1099-NEC Gummed Seal Double-Window Security Tint Envelopes are designed specifically to fit three-per-sheet 1099-NEC forms, making them ideal for bulk mailing. Crafted from 24 lb white wove paper, each envelope features a security tinted pattern and precisely aligned windows to ensure that sensitive, confidential information is kept private. Gummed flaps seal securely with moisture. "Important Tax Return Document Enclosed" is printed on the front face.