Agena 1.25" Starguider Dual ED Eyepiece - 15mm The Agena StarGuider Dual ED eyepieces feature high contrast, 2 element ED glass Wide 60 degree Field of View (FOV) in 5mm to 25mm focal lengths Exceptional at nearly eliminating lateral color aberration and light scatter while retaining excellent sharpness, contrast and definition Perform as well as other, more expensive Orthoscopic and Plossl eyepieces