Made of anodized aluminum and unused in the original box! Use this to give your straight up and down compound microscope a 45 degree angle for easier viewing and less neck strain. Swivels 360 degrees and has a set screw to lock it in place (also a set screw for the eyepiece). Contains an equilateral prism to create the 45 degree angle. Threads to attach this to your microscope are 30mm diameter. Standard 23mm microscope eyepieces fit. An incredible value!