Hearts in Sync $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". Hearts in Sync quantity Add to cart SKU: 854. Category: Hearts. Related Products I Only Have Irises for You $20.00 Squeeze the Day $20.00 Wishing You a Bee-You-Tea-Full Day $20.00 Bless Your Heart $20.00