The Gates SWP25B Fathom "Signature" Wide-Angle Port gives you a super wide 110° field of view with full zoom-through capability, a result of partnership with Fathom Imaging, bringing distortion-free imaging to Gates HC, PC, MC and TRV series housings. This port is backward compatible with many out of-production Gates housings so current users can upgrade to one of the finest ports available for underwater imaging.
The SWP25B super wide-angle port contains several lens elements with a proprietary anti-reflective coating, to provide a magnified view supplementing the camera optics, free of distortion and very high resolution. It provides both a 110° super wide field of view, and full zoom through capability for ~1.5in / 38mm macro. This is unprecedented as it affords a huge range of imaging choices without changing ports.
While the front dome element has a hard coating and is protected by a shade, it is not field replaceable, so care must be exercised to avoid contact with sharp objects (like coral).