This focusing Helicoid tube is made with standard M42 mount Lens and M39 mount Camera. This adapter made with Copper core, high quality and stable.The length of this Helicoid tube 25mm (min) to 55mm (max).Independent product assembly, There will be 1 to 2mm deviation.This Helicoid tube is useful for those lenses without focus ring, It could be used as Macro barrel and offers fine focus control for macro photography.Made of Anodized Aluminum in Black finish with high quality. It will be better when you use it with filter adapter together.Install:Firstly attach your M42 lens to this tube. then attach the lens and helicoid tube together to your M39 camera.Material: Metalcolour: blackPackage Contents:1 x M42-M39 25-55mm Focus Adjustable Helicoid AdapterOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.