S = 50-piece pack, M = 100-piece pack.The envelope you use for invitations creates the first impression on guests. These A7 envelopes feature a vintage elegant look suitable for any occasion. Simple unadorned design conveys sincerity. High quality well-made envelopes measure 5.25 by 7.25 inches fitting 5x7 cards and photos. Easy to use wet glue and press for seconds. Good value 100 pack sufficient for daily use or small business. Weight: 0.79 pounds.