1. Amplification coefficient 0.7X~0.8X underwater. 2. The design of optical glass and antireflective coating-film makes the image perfect without distortion. 3. This device was created to correct the view angle underwater. 4. 67mm thread on the wide angle correctional dome port lens ensures an ease of access and mobility when most needed. 5. Ideal for diving, surfing, snorkeling, skiing, yacht or other activities. 6. Note: Only for camera with microspur.