Standard 1.25in diameter for 1.25in eyepiece and With a metal pressure rings; it can damage and scratch when the eyepiece is used with the strong stability Wide 90degree angles; can view correct picture from stand and look down with a comfortable angles This locking screws which can firmly with the and eyepiece; and the installation is stable without shakings and affecting pictures with M 28.5x0.6mm filter thread which connection of 1.25inches filter The diagonal lens with enhances aluminum molds, which have highly light transmittance