Feature:1. Small apertures of different diameters are provided in the optical system to meet different light transmission requirements.2. Change the diameter of the aperture by the handle.3. Metal material, reliable performance, durable.4. We provides 5 kinds of aperture for you to choose from to meet different requirements.5. Compact and practical design make the diaphragm works more stable.Specification:Item Type:Iris DiaphragmSK25:Magnified Diameter: 1.5-25mmMaterial: MetalOuter Diameter :44mmInner Diameter: 25mmThickness :8mm14 bladesSK23Outer Diameter: 37mmMinimum Aperture Diameter: 1.5mmMaximum Aperture Diameter: 23mmMaterial:MetalThickness: 7.0mm12 BladesSK12Outer Diameter: 19.8mmMinimum Aperture: 1mmMaximum Aperture: 12mmMaterial: MetalThickness: 5.0mm10 BladesSK8Outer Diameter: 14.8mmMinimum Aperture: 0.8mmMaximum Aperture: 8mmMaterial: MetalThickness: 4.5mm8 BladesSK6Outer Diameter: 13.0mmMinimum Aperture: 0.8mmMaximum Aperture: 6mmMaterial: MetalThickness: 6mm8 Blades.Package List:1 x Diaphragm