): The smallest standard US size for greeting cards and formal invitations. ( ): Fits A4 paper folded twice or A6 cards. Specialty Mini Envelopes : Often measure around
: Used for social correspondence and events. C7 ( ): A standard European size for RSVP or "Thank You" cards. 4-Bar / A1 ( buy small envelopes
and are used for business cards, gift card holders, or wedding placeholders. Where to Buy ): The smallest standard US size for greeting