Available sizes: 
A7 (5 1/4 x 7 1/4) - $0.55 each
 
Sealing method: Wallet Peel & Press™
Paper weight: 80lb
Metric size: 133mm x 184mm
 
A7 Envelopes are commonly called 5 x 7 Envelopes because they are the best envelope for 5 x 7 cards.