First launched in 1983, it is used in orthoptic and ophthalmic clinics and by optometrists world-wide.

Tests for stereopsis using natural vision, with no  special glasses. It has three transparent plates, which are presented to the patient one at a time against the clear background provided by the fold-down flap of the storage box.

Tests for stereopsis, even if reduced vision or amblyopia is present because of the coarse texture elements included in the pattern.