GSO 1.25″ 5X Achromatic Multi Coated Barlow Lens

Barrel size = 1.25″ (31.7mm) Magnification factor = 5x Weight = 108gm Total height = 3.46″ (88mm) End caps = 2 1.25″ filter threads on bottom of Barlow: No Made in Taiwan Please note: This is a very high magnification Barlow. It is not for everyone or for common viewing conditions. Before buying, please make sure that you are using realistic magnifications with your telescope. A good rule of thumb is that under very good conditions and with a very good telescope, the maximum power you will be able to use is about 50x of magnification per inch of telescope aperture. With average telescopes and/or average conditions, you should be able to use 30x of magnification per inch of telescope aperture. So for example, if you have a 6″ telescope, under typical conditions you will be limited to 6×30 = 180x of magnification, and 6×50 = 300x of magnification at best. Boosting the magnification beyond this recommended maximum for your telescope aperture is not realistic. This is bound to result in image break-down, causing fuzzy images, focusing difficulties, increased color around objects (caused by other optical elements in the telescope which are magnified by the Barlow) and general disappointment, but this is not a fault of the Barlow.