Description: Material: Crafted from PVC material, this red green reading card ensures longevity and resilience, providing a reliable training aid that withstands regular use Product Size: Available in two convenient sizes to suit different needs, large 28.4cmx21cm and small (21cmx14cm, offering flexibility for various training environments or personal preferences Feature: It needs use with red green glasses, vision cards, letter cards or black letters in/with white background Function: This set are amblyopia vision training reading aids. Help correct amblyopia ,improve simultaneous perception and fusion vision ability Package Includes: Each purchase includes two red green reading cards, ensuring you have the necessary tools to start your training sessions immediately Specification: Material: PVC Size Chart: 28.4cmx21cm/11.18inchx8.27inch 21cmx14cm/8.27inchx5.51inch Package Includes: 2 Pieces Red Green Reading Card Note: Please allow slightly errors 1-2cm/0.39-0.79inch differences due to manual measurement.