Happy Bird Day $20.00 Inside Message Blank Inside Packages of Heartstrings® cards are shrink-wrapped and sold in sets of 10 cards with envelopes. The actual card size is 4 1/4" x 5 1/2". Happy Bird Day quantity Add to cart SKU: 1059. Categories: Birthday, Women. Related Products I heard by word of mouse $20.00 Flowers Chase the Blues $20.00 Make time to play $20.00 When You’re Over the Hill $20.00