Function: 1 The M42 adjustable aperture is used to adjust the light from the camera lens. 2. Full manual control, manual adjustment of scale focus, aperture prioritization, unlimited focus 3 Lens adapter ring, top and bottom ports are M42 ports. Opening diameter range: 1.5‑25mm / 0.1‑1.0in 4 Simple design, small size, lightweight, easy to carry and use, convenient and practical. 5 High quality metal material, reliable performance, sturdy and durable, long life. Specifications: Item Type: Lens Adapter Ring Material: Metal Color: Black Weight: Approx. 50g / 1.8oz Interface: M42 to M42 1.5-25mm / 0.1-1.0in Minimum Opening Diameter: Approx. 1.5mm / 0.1in Maximum Aperture: Approx. 25mm / 1.0in Package List: 1x Lens Adapter Ring >