Features:

Rechargeable battery built inside;
Red/Green Glasses and one pen light included;
Nice case for safe storage.
Strabismus Amblyopia Optometry Worth 4 Dot Test with Red Green Glasses

Product manual:

The four round hole-shaped lights of the inspection surface of the lamp are arranged in a prismatic shape. Horizontal two for the green, vertical two (above the red) side for the red, the bottom is white. Check the inspectors to bring red and green glasses. In accordance with the habit, the general right eye for the red lens, left eye for the green lens.

Specifications:

Product Name: Worth 4 dot
Material: high strength alloy material
Battery: with 18650 Battery
Size: 15cm x 4.5cm (APPROX)