Jay Photonics' Oil Darkfield condenser reveals hidden details of your samples with high-definition darkfield illumination when attached to our Si-Through-HR Microscope. This oil darkfield condenser has a numerical aperture (NA) between 1.25 and 1.36, which is suitable for microscope objective with NA of 1.25 or less, which is the case for our 100x oil objective (NA 1.25) included with our microscope.