In addition to the primary aperture, many foraminifera have "supplemental" apertures. Other shaped slits were used, including vertical and diagonal apertures. Various sized apertures were positioned around the sleeve. These lenses are those with maximum apertures of f/2 or larger. Aphids have a tail-like protrusion called a cauda above their rectal apertures. A fourth wheel was fitted with five beam apertures and two gobos. Both depth of field and depth of focus increase with smaller apertures. These were removed between 1975/6, with small plates welded over the apertures. Equation () holds for both square and circular apertures. Also termed immersion lithography, this enables the use of optics with numerical apertures exceeding 1.0. Some foraminifera have "toothed", flanged, or lipped primary apertures. The earth pin is centred between the apertures, offset by . Sockets are required to have shutters for the line and neutral apertures. Plants regulate the rate of transpiration by controlling the size of the stomatal apertures. The hot air could escape through the apertures at the aileron hinges.