Sirui is a small Chinese manufacturer that makes anamorphic lenses (1.33x) for video use. These lenses "squeeze" a wider scene into a narrower capture, and require post production to desqueeze them. What this results in is that 16:9 video turns into a more movie-like 2.4:1 format. Besides the additional scene width, anamorphic lenses have that distinction horizontal flare you may have seen in films, as well as an oval bokeh (as opposed to round).