Orion 08704 Tri-Mag 1.25-Inch 3x Barlow Lens (Black) Delivers a 3x magnification boost to any 1.25 inch telescope eyepiece, greatly increasing your available viewing magnifications For example: The Orion Tri-Mag 3x Barlow makes a 15mm eyepiece yield the same magnification as a 5mm eyepiece (15/3 = 5) Great for high-power lunar and planetary observations Perfect for extracting higher powers from short-focal-length telescopes Threaded to accept standard 1.25 inch Orion eyepiece filters