Assess the near visual acuity of 2- and 3-year-old children or use the cards at any age (older than 2+ years) to train an amblyopic eye. Set contains 3 packs of 16 domino-like cards with a large symbol at one end and a small symbol at the opposite end. LEA SYMBOLS® sizes are 3.2M and 0.8M, 2.0M and 0.5M, and 1.25M and 0.3M. Each symbol on the card is printed with its M unit, decimal value, 6 meter and 20 foot equivalency for visual acuity value at 40 cm testing distance. Includes training cards and instructions. Paper cards measure 1.6" x 2.75" (4 cm x 7 cm).