The Sandel Avionics SN3308 is the first really new general aviation flight instrument to come along in the last 20 years, and certainly the first one expressly designed for use in the GPS age. It's the first all-electronic flight instrument to fit in a three-inch panel opening, and consequently the first one that can be accommodated by a standard GA instrument panel layout. Accomplishing this was no mean feat. The largest conventional CRT or LCD color displays that will fit in a standard three-inch opening have a viewing area of about 2 1/4 inches square. That's simply not big enough for a primary flight instrument. An EHSI based on such a display would have a compass rose substantially smaller than a conventional three-inch mechanical instrument, and would have no room left for all the other information that an EHSI should display.