Friends Keep you Growing $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". Friends Keep you Growing quantity Add to cart SKU: 101. Category: Friendship & Support. Related Products Share an Umbrella $20.00 You Will Never Fly $20.00 Chocolate for My Bud $20.00 Friends are the Fiber $20.00