Prima Altered Box Artist Trading Card Set - White. Prima Altered ATC Card Set features 52 - 2 1/4 inch X 3 1/2 inch white cards. **PLEASE NOTE** ATC CARDS ARE NOT 2 1/2 IN. X 3 1/2 IN. THEY ARE 2 1/4 IN. X 3 1/2 IN. They are perfectly sized for small works of art, these cards are great for mixed media, cards and more. Specifications: Box measures 2.88 in. x 4.79 in.