Orion 10087 EON 115mm ED Triplet Apochromatic Refractor Optical Tube Assembly (White) A beautifully constructed, 115mm (4.5 inch) aperture triplet ED apochromatic ideal for both astrophotography and serious visual observations Fully multi-coated, three-lens ED optics and versatile f/7.0 focal ratio yields high-contrast images with excellent color correction and sharpness Rock-solid, rotatable 3 inch dual-speed (11:1) Crayford focuser provides precise focus control and stable support of imaging accessories Includes two split-clamp tube rings, narrow dovetail bar, thread-on metal objective cap, and a hard case with a custom die-cut foam insert for protection during transport and storage Relatively lightweight 15.2 lb. optical tube can be stably supported by medium-size equatorial mounts