Macro Extension Tube for C Mount Lenses black Macro Ring for C Mount CCTV Lenses, 25mm 35mm 50mm and others, which can be adapted to Micro 4/3 (requires a C Mount to Micro 4/3 adapter, sold separately). 25.4mm Screw C-mount The macro ring moves the lens farther from the film or digital sensor. The farther away the lens is, the closer the focus, the greater the magnification. These macro rings can be stacked for even closer focus. This extension tube does not affect image quality as there is no optics inside. In comparison, close up lenses are often blamed for degrading image quality. The more tubes you add, the closer the focus and the greater the magnification. Specification: Ring height(without screw part): 5mm Screw mount: 25.4mm Package includes: Macro Extension Tube x1 Fitting for: C-mount Lens.