The A1 Contour Flap Envelope (3 5/8 x 5 1/8) in 80lb. Midnight Black is a rich jet black colored invitation envelope. It features an elegant, deep plunging contour flap, peaked with a slight curve at the tip, and is suited for RSVP cards, invitations, announcements, and notes. This envelope is sealed by an adhesive strip, and its dimensions make it the most common envelope used for RSVP as the A1 size fits inside all other "A" envelope sizes. Available both plain and printed for customization, branding and creative uses, starting in small quantities of 50 to large quantities of 50,000 and more.