As the standard type: Landolt CCheck the distance: 5m, 2.5mCheck the range: from 4.0 to 5.3Sight record: five records, decimals records, scores recordedVision Light Box Size: 5m 846 * 283 * 18 mm                          2.5m 710 * 283 * 18 mmProduct Code:WH20 indoor hanging-type (5m): hanging, with a direction stick.WH21 indoor hanging-type (2.5m): hanging, with a direction stick.

C ring visual acuity chart