In stock, ready to ship! This is a 10X PLAN infinite microscope objective with RMS thread. The NA is 0.25 and requires a 180 mm or longer telephoto lens or a tube system. Effective working distance is around 11 mm. It is an excellent choice to start with higher magnifications. Because it is an infinite objective, magnification can be varied by using different focal length tube lens. For example, when a 200mm lens is used as tube lens, magnification is 10x200/180 = 11.11x. Our advise: We recommend to use this objective together with our tube systems (with Raynox DCR-150) for sharper results up into the corners and edges. On some tele lens with a larger zoom area vignetting and decreasing sharpness could be possible. This 10X is (like the Generic Plan 4X) a good microscope objective for beginners. Can be used with all our focus stacking rail series. If you want to use it with your tele lens, you will need a RMS adapter. It has been tested that with some tele objectives there could be some vignetting on full format cameras if objectives is less than 180mm.