The optional 135mm Macro Port can be used in place of the housing's original port to shoot extreme close-up photography underwater. The original lens port is removed and the 135mm Macro Port simply threads into the front of the housing for quick and easy installation. The Macro Port is optimized for use with the camera in the 100mm to 135mm focal length range, with or without an external macro lens. We recommend using the 135mm focal length combined with the camera's built-in digital teleconverter function for some incredible macro shots to rival much more expensive DSLR and mirrorless systems.