[A4 slightly larger (square size 2) 20 sheets]

[A4 slightly larger (square size 2) 25 sheets]

[A4 (square size 20) 25 sheets]

[A3 (square A3 size) 90 Sheets]

[B4 (B4 corner No. 1) 25 sheets]

These durable and secure cardboard business envelopes are easy to open and convenient. The contents are shipped without folding, and the single zipper in the tongue is easy to open and will not take out any trash.
Re-usable for document storage after opening (indexed) Fits B4 sizes
Size:400mm*300mm+65mm Product Weight: Approx. 3.9 oz (108 g). Weight: 350 g/m2 Pack of 25 Comes with self-adhesive tape for easy sealing. This product is made of eco-friendly products.

From the Manufacturer

Maruai B4c Envelopes, B4 Compatible, Cardboard Envelopes, Business Envelopes, Tape, 25 Sheets

Size: B4 (B4 Square No. 1); Size: 15.7 x 11.8 x 2.6 inches (400 x 300 x 65 mm); Number of sheets: 25 sheets; Specifications: Tape-type one-touch [Country of origin] Japan