Unitron Phase Contrast Microscope Objective Suite consisting of a 10X Dark Medium Phase Objective, n.a.: 0.30, 20X Dark Medium Phase Objective n.a.: 0.45 and a 40X Bright Medium Phase Objective, n.a.: 0.65. These are 170mm TL objectives of the short mount variety. All are in nice cosmetic condition and optically excellent. As a side note, the 40X BM objective is a rare bird. Thanks for looking!