All ears are different, and the degree of difference within the bounds of acceptability is remarkable. To that end, the keys to construction, reconstruction, or modification must be observed in order to mold an ear that "looks right." Simply stated, these keys are as follows: The ear is a flap approximately 50 to 60% as wide as it is high, sitting back one earlength (6.5 to 7.5 cm) from the lateral orbital rim, with the top of the ear level with the brow inclined approximately 20 degrees and protruding 1.5 to 2.0 cm from the head. It is composed of five critical elements: concha, helix, antihelix, tragus, and lobule, and parts of lesser importance including antitragus, intertragic notch, and Darwin's tubercle. The subtleties of form and proportion of its features will be revealed by careful observation and study.