Tully-Fisher relation for our detected PRGs (red stars), compared with other PRGs (black triangles, Whitmore etal. 1990; van Driel etal. 2002; Iodice etal. 2003), and normal spirals (black dots, Giovanelli etal. 1997). The I absolute magnitudes, with uniform photometry and distance corrections, are plotted vs. observed rotation velocities (full width at 20% power), in the polar rings.