A-Style square flap envelopes are classified as social announcement types of envelopes, with a square flap design.

Size Dimension (inch) Dimension (mm)
A-2 4.38 x 5.75 in 111.12 x 146.05 mm
A-4 4.75 x 6.50 in 120.65 x 165.10 mm
A-7 5.25 x 7.25 in 133.35 x 184.15 mm
A-8 5.50 x 8.13 in 139.70 x 206.37 mm
A-10 6.25 x 9.63 in 158.75 x 244.47 mm
SLIM 3.88 x 8.88 in 98.42 x 225.42 mm

These envelopes come in a wide variety of colors and textures and it is usually produced by text weight papers. A-style envelopes can be used for invitations, smaller brochures, booklets and promotional pieces, as well as business stationery, for a unique premium look.