Orion 52026 2-Inch Precision Centering Extension Adapter (Black) Handy extension adapter precisely centers 2 inch eyepieces or accessories in a telescope's 2 inch focuser Features a lateral compression mechanism for delightfully accurate centering of 2 inch accessories Centering rollers will not scratch or mar inserted eyepiece, collimating device, or other accessory barrels Ideal for accurate collimation tool use in reflector telescopes Adds 1.7 inch" (43mm) of extension