Mead #10 - White Legal Envelopes, 40-ct. Boxes Size 4 1/8 x 9 1/2 (Set of 2) All purpose #10 envelopes are the perfect size for business correspondence, letters, invoices, and brochures! Great for personal or office use, plus they have printed linings for added security. Set of 2 - 40-count boxes of 4 1/8 x 9 1/2 Mead security envelopes.