Princess for a 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". Princess for a Day quantity Add to cart SKU: 10145. Categories: Friendship & Support, Hearts. Related Products Squeeze the Day $20.00 It’s not Which Way We Face $20.00 The Plot Thickens $20.00 Thanks for Your Strength $20.00