Nikon Microscope Objective BD Plan 100x0.8 ELWD Japan

Nikon Microscope Objective BD Plan 100x0.8 ELWD Japan. Never used this as I didn't get the microscope it was for, it looks to be in good condition. I understand the letters on the objective to mean the following BD= biright and darkfield, Plan = plain, ELWD = extra long working distance.