Adjustable iris aperture：sizes m30 to m37,apertures1.5-26mm iris,min Diameter1.5mm, Max Diameter26mm Reliable Materials:Aviation metal,Rugged and very reliable performance Simple Operation: Just use the handle to change the aperture diaphragm diameter, which is easy to operate and more directly for adjustment. Type: Lens Reversing Adapters,adjustable iris diaphragm for PVS 14 night vision deviceand other equipment Product Includes:Adjustable Aperture Filter*2 2 Pack Adjustable Iris Aperture Diaphragm Filter Pack M30 to M37 Iris Aperture Diaphragm Adapter Optical Diaphragm 1.5-26mm Lens Module Adapter Ring PVS-14 PVS-31 Optics