Size: #10 Window Envelopes (4 1/8 x 9 1/2) ^^ Color - 24lb. White ^^ #10 window envelopes are commonly used for mailing invoices, statements, letters, and other business correspondence. They are also suitable for personal use, such as sending greeting cards, invitations, or personal letters. The window design allows for the recipient's address to show through, making them ideal for bulk mailing and ensuring accurate delivery. ^^ #10 window envelopes are commonly used for mailing invoices, statements, letters, and other business correspondence. They are also suitable for personal use, such as sending greeting cards, invitations, or personal letters. The window design allows for the recipient's address to show through, making them ideal for bulk mailing and ensuring accurate delivery. ^^ When using #10 window envelopes, it's important to ensure that the contents are neatly folded to align with the window for a professional presentation. Additionally, double-check the recipient's address to ensure it is visible through the window and accurately positioned. For bulk mailing, consider using address labels or printed envelopes for a more efficient process.