Hot M42 To M42 Lens Adjustable Focusing Helicoid Macro Tube Adapter-17mm To 31mm M42 to M42 Mount Lens Adjustable Focusing Helicoid Macro Tube Adapter - 17mm to 31mm_x000D_ The all-metal adapter is designed to fit the lens securely, yet can still be removed easily when not needed._x000D_ Introduction:_x000D_ This tube useful for lens without focusing ring. And it can be use as macro extension tube. There is no electronic elements in the adapter. aperture and focusing must be manually control._x000D_ Material: aluminum alloy_x000D_ Made of Anodized Aluminum in Black finish with high quality._x000D_ The length of this Helicoid tube is 17mm (min) to 31mm (max),it offers a total of 14mm movement distance for the lens focusing._x000D_ You can use M42 screw mount lenses, such as Carl Zeiss or Pentax 42mm screw mount lenses, and even enlarger lenses._x000D_ This Helicoid tube is useful for those lenses without focus ring, Tube offers fine focus control for macro photography._x000D_ This focusing helicoid tube is made with 42mm front mount and standard 42mm rear mount and is made with light-weight alloy._x000D_ It could be used as Macro Barrel._x000D_ Automatic diaphragm, auto-focusing will not operate correctly while using this adapter. Manual focusing with A/M mode metering is ok with the adapter._x000D_ Compatible With:_x000D_ M42 Lens & Camera_x000D_ Package Include:_x000D_ 1 X M42 to M42 Mount Lens Adjustable Focusing Helicoid Macro Tube Adapter - 17mm to 31mm_x000D_ Only the above package content, other products are not included._x000D_ Note: Light shooting 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. _x000D_ _x000D_ _x000D_ _x000D_ _x000D_ _x000D_ _x000D_