| This Nagler Type Five eyepiece uses a new six-lens design that reduces the size and weight of this 31mm eyepiece to less than that of the previous generation 20mm Nagler. Had the previous-generation seven-lens Nagler design been used in a 31mm focal length, the resulting eyepiece would have been the size and weight of a bowling ball! The six-lens design uses multiple rare earth glass elements. Some of the lenses are actually over 70mm (2.75") in diameter, larger than the objective lens of the TeleVue Pronto telescope! Please note the 35 ounce weight of this superb eyepiece, however. It may pose a balance problem with some Dobsonians when switching to the 31mm from a much lighter shorter focal length 1.25” eyepiece. Its use may require some temporary rebalancing of your scope, or the use of a TeleVue #TVEQC equalizing adapter with 1.25” eyepieces to avoid balance problems. While easily the most expensive commercially-available eyepiece made, it is a surprising best-seller, particularly with owners of large premium-quality Dobsonians who swear by its huge exit pupil and "picture window on space" performance. | 
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