1. Retina pattern has accurate colour rendition with the physical dimension matching length ratio. 2. Ametropia (-5.00D to +4.00D) ,You can put any power on it to train,inculding the cylinder lens. 3. 3 levels of difficulty with change in the pupil size (3, 5, 7mm) ,Switchable by simulation of small, general and mydriatic pupil. 4. 3 layers of arc walls for refraction lenses or setting of different degrees of astigmatism and axial cylinder. 5. Degree of astigmatism axial angle disk is 0~180 . Flexible stand with height adjustment. Size: 130x80x80mm. Color: Black Material: Plastic+Metal Package Contents: 1 * Refractive examination exerciser Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.