Features MICROSCOPE APERTURE: The thread diameter of the diaphragm is M42 to M42, the number of blades is 14, fine workmanship, durable. ADJUSTABLE INNER DIAMETER: The diaphragm is adjustable from 1.5 to 26mm, with an outer diameter of 45mm, in an optical system to meet different through lighting requirements. METAL MATERIAL: The light diaphragm is made of aluminum alloy and stainless steel for reliable performance and durability. EASY OPERATION: The user can change the diaphragm diameter by the handle, and the diaphragm inner diameter can be adjusted. COMPACT AND SMALL: The compact and practical design of the diaphragm makes the diaphragm a more practical way to work. Specification: Item Type: Microscope Aperture Material: Aluminum alloy, stainless steel Inner Hole Diameter: Approx. 1.5-26mm / 0.06-1.02in Outer Diameter: Approx. 55mm / 2.17in Thickness: Approx. 17.5mm / 0.69in Number of Blade: 14 pieces Thread Diameter: M42 to M42 Package List:1 x Microscope Aperture Package List 1 x Microscope Aperture