Tele Vue 3X Barlow - 1.25" (Pre-owned)In excellent condition About the TeleVue 3X Barlow 1. 25" Properly designed Barlow lenses do wonderful things: They amplify power, slow the telescope''s f # (improving eyepiece sharpness), and give designers the opportunity to compensate for telescope eyepiece aberrations. Tele Vue Barlow Lenses use multi coated high index glasses for optimum aberration correction, exceptional contrast with virtually no light loss. Observed performance is aberration