Mirror telephoto lens by Sigma, 600 mm, f 8.0, manual focus in mount for Nikon Ai. Very good condition. Includes case, instructions, screw-on lens hood, integral tripod mount, front and rear caps. Also includes a set of four rear-mount filters (ND-4x, Y-52, O-56, and R-60). Asking $150 including ground shipping in continental U.S. Prefer cashiers check or money order. Thanks for looking.