If you have a Fuji X mirror-less camera and also some old M42 screw thread lenses, then this is the kit for you. Fit this between the camera and the lens and you have a perfect, stable conjunction between the two.It has been made out of what appear to be good materials, brass I believe, with what appears to be good metal mounts at either end.There is, of course a down side to using these adapters and that is that you have to manually focus the lens, manually set the aperture, and because of the crop factor of the APS-C sensor a 50mm lens is halved again and becomes a brilliant 75mm portrait lens, but with the advantages of the 50mm lens - in other words the depth of field remains the same, as does the aperture so you do not lose any speed of the lens with this adapter. For an example if the 50mm lens was a f1.4, then on this adapter it becomes a 75mm f1.4!! Try buying one of those for this sort of money.Many may find this a backward step, but it is something that you soon get used to doingThe advantages are that M42 screw thread lenses can still be acquired cheaply by today's standards, some as cheap as £20-30. Add the prices of the adapter and you still have a very cheap lens, especially when you consider that Fuji XF lenses tend to sell at about £500-600, and remember a lot of these old lenses are built solidly of metal and glass with hardly a glimpse of plastic anywhere. Treated well will last a lifetime as well as given brilliant results.