ESCRIPTIONS:- Fly Stereopsis Test with LEA Symbols® Designed to rapidly test for amblyopia and strabismus using gross thru fine stereopsis (4800 to 20 seconds of arc). Graded circle test from 400 seconds now down to 20 seconds with no monocular clues. New improved booklet has answer key on back cover and includes polarized viewers. Specifications:- Graded circle test from 400 seconds now down to 20 seconds. No monocular clues with NEW Technology. New improved booklet. Answer key on back cover. Includes both adult and pediatric polarized viewers