A1 Envelopes - White 80lb - 3 5/8 x 5 1/8 (for response cards) (pack of 50) Envelope Size: 3 5/8" x 5 1/8" Fits Card Sized: 3 1/2" x 5" 80lb paper weight (premium quality) Square Flap (gummed) bright white (96 brightness)