The Maddox insert in red is a precision optical accessory designed for use with Risley rotary prisms during vision testing and training. This specialized occluder insert helps practitioners assess binocular vision, phoria, and eye alignment by selectively blocking light to one eye while allowing the other to view through the prism. The red lens provides enhanced contrast and reduces glare, making it ideal for clinical settings where accurate vision screening is essential. Compatible with standard Risley prism frames, this durable insert is a reliable tool for optometrists, ophthalmologists, and vision care professionals performing comprehensive eye exams and vision assessments.