The focal length should be 210mm, and the distance between the magnifying glass and the text should not exceed 210mm to avoid eye dizziness.
DELUXE A5 FULL PAGE MAGNIFYING SHEET PVC GLASS READING SEWING MAGNIFIER SCREEN
Book Magnifier for Reading Large Sheet Magnifier Reading Aid Glass 3X Page
3 pcs A5 Full Page Magnifier Sheet Magnifying Glass Reading Aid Lens 3X Big
A5 Full Page Magnifier Sheet Magnifying Glass Reading Aid Lens 3X Big
5pcs Book Magnifier Bookmark: 3x Shatterproof Thin Lens - A5 Full-Page
5pcs Book Magnifier Bookmark: 3x Shatterproof Thin Fresnel Lens - A5 Full-Page
