Abstract: Non-contacting face seals having sliding rings with grooves formed in the lateral planes thereof. Each groove has inlet and outlet ends, with the traverse cross-section of the groove decreasing from the inlet end to the outlet end. The outlet end of the groove defines a recess of approximately 7 microns in the lateral plane. The bottom surface of the groove curves longitudinally and transversely, with a maximum curvature of about 4 microns. The lateral edges of the groove are of different lengths, so that one extends farther from the plane of the sliding rings than the other. The grooves have a variety of shapes, including spiral, double crossed spiral, and others. The seals help maintain high accuracy and dimensional repeatability of the grooves in the sliding rings for industrial and manufacturing applications.