Bids Are Invited For Snellen Signs Scale (Visual Acuity Chart) Optotype Scale (Letters) In Snellen E Format. Constructed In Washable Rigid Or Semirigid Material, Such As Expanded Pvc Or Polystyrene, With Resistance To Moisture. Frame Dimensions: 50Cm Height X 70Cm Height, Letters Must Be In Black On A Matte White Background, With Good Visual Contrast. It Must Contain The Logo Of The Sus And The School Health Program And An Ophthalmological Occluser Made Of Non-Toxic, Lightweight And Resistant Plastic, With Rounded Edges. Anatomical Paddle Type Shape, With Support Handle That Allows Safe And Comfortable Coverage Of One Of The Childs Eyes. Color: Black Or Neutral. Reusable, With Smooth Surface And Washable With 70% Alcohol. Approximate Measures: 8Cm X 6Cm, With 12 Cm Cable