Do crafts Paper mania Square Aperture Card Blanks come with envelopes and is acid and lignin free. The cards are a thick 300 gsm and the envelopes are 120 gsm. The cards are tri-fold window cards with a small square aperture cut out for photographs to be inserted. It is ideal for making your very own greeting cards, invitations, etc. It is available in a cream color. It is designed in the UK. Each card measures 13.5 cm length by 13.5 cm width with a small aperture in the center.