Feature 1、Adjustable Inner Diameter: The aperture diaphragm has an adjustable inner diameter of 4.5 to 25mm, an outer diameter of 42mm, and a thread diameter of M36. 2、Function: The aperture diaphragm provides small holes of different diameters in the optical system to meet different light throughput requirements. 3、Easy to Operate: Change the diameter of the aperture diaphragm by the handle, very easy to operate in practice and friendly to novices. 4、Aluminum Alloy and Stainless Steel: The camera aperture diaphragm is made of aluminum alloy and stainless steel for reliable performance and ruggedness. 5、Compact and Practical: This aperture diaphragm uses a compact and practical design, making the aperture diaphragm a more practical way to work. Item Type: Aperture Diaphragm Material: Aluminum alloy, stainless steel Inner Hole Diameter: Approx. 4.5-25mm / 0.18-0.98in Outer Diameter: Approx. 42mm / 1.65in Number of Blades: 14 Thickness: Approx. 10mm / 0.39in Thread Diameter: M36 Package List 1 x Aperture Diaphragm