This is a 35 mm Petri dish with a 10 mm hole through the center. This is the bottom well of a petri dish set and is usable with any standard 35 mm cover. It is ideal for imagin equipment and designed for use within an AFM with an undermounted microscope. It has broader applications for fluid cells and more. It is recommended to purchase this in detailed acrylic. Imaging through the material itself is not guaranteed. This design is meant to be a cost effective solution for consumers. Please report any issues with the design as this is a young design.