Product details:

All new dome port system utilizing a new 4 radius dome and interchangeable mounting body lengths. Most lenses do not perform any better with a larger dome than with the exceptional 3 radius dome ports except for lenses marked as recommended in the port charts. Edge sharpness with either dome system may be enhanced by the addition of a +2 diopter close-up lens. Over-under photos may be easier with the larger dome. The #5510.22 has been optimized to operate with the Nikon 12-24mm zoom lens or Canon 10-22mm zoom lens. Addition of a +2 diopter close-up lens to the camera enhances corner sharpness.