Boston International Worth Keeping Dolphin 4D Art Card Worth keeping 4D card, simply scan and enjoy the magic Easy: download free 4Dscan at google play or app store, scan the worth keeping postcards, and watch as 3D becomes 4D Cards are 6 x 6-inches, envelope Included; vivid colors even as a 3D card Makes an Extra special birthday or greeting card, one they'll find worth keeping 4Dscan works with Iphone 4S and up, and android phones 4.0 and up