Detailed Underwater Viewing: The 4″ optical-grade lens offers distortion-free magnification with a focal range of 3 to 8 inches, bringing corals, fish, and aquarium details into sharp focus.Powerful Magnetic Design: Equipped with strong rare-earth magnets that hold securely to glass or acrylic up to 5/8″ thick, allowing smooth, hands-free repositioning for clear underwater viewing.Ideal for Coral & Fish Observation: Designed for monitoring coral health, spotting small details, or setting up close-up photography, allowing clear viewing of aquarium life.Durable & Secure Build: Rare-earth magnets ensure a strong, stable hold, while the optical acrylic lens provides clear visibility and lasting performance on both glass and acrylic surfaces.Built with durable materials and precision engineering, the DeepSee 4″ magnifying glass provides reliable, long-lasting performance and clear underwater viewing for aquarium enthusiasts.