Features: Accuracy, suitable for ophthalmologists and optometrists perform eye examinations. Make of quality PVC material, easy to clean. The scale is clearly visible, and can accurately measure eye problem. It is mainly use by ophthalmologists, optometrists and opticians. Can also be use by students and family to facilitate self-testing. Widely used in eye clinic, optometry room, opticians and other professional place, it can used for eye examination and testing during optometry. At the same time, also suitable for simple eye tests home and school. Specifications: Material: PVC Size: As Shows Pattern: Multiple pattern, please refer to the picture Note: Please allow 1-2cm errors due to manual measurement. Due to difference between different monitors, the picture may not reflect the item actual color. Package includes: Package 1: 1x PD Ruler Package 2: 1x PD Ruler Package 3: 1x Eye Occluder Package 4: 1x Eye Chart