The Nimar Flat Lens Port for Canon EF 100mm f/2.8 Macro/L Macro is a flat glass lens port for an underwater Canon camera housing. It fits an EF 100mm f/2.8 Macro USM or L Macro IS USM Autofocus lens. See Port Chart. Flat ports magnify an image more than spherical or dome ports and are better for extreme close-up shots. This one has a depth rating of 197'.