Having a special theme party or event with black as the main color? These deep, black, No. 10 square flap envelopes will complete that sophisticated look for your occasion. These 80# text weight, smooth finish envelopes will elegantly enclose your corporate letterhead paper, special occasion letter, or Save the Date wedding card. Try addressing these envelopes with white, metallic, or colored gel pens, calligraphy writers, or markers to make your project stand out from the rest.