[PREMIUM QUALITY] Made from aluminum alloy and CNC manufacturing, this 1.25-inch collimation eyepiece is built to last. [EASY TO USE] Simply insert the eyepiece into the tube and adjust the screws until the black spot is centered for successful collimation. [VERSATILE TOOL] Ideal for calibrating the optical axis of a reflector, this eyepiece is a must-have for astronomy and photography enthusiasts. [SHORT SIZE DESIGN] Compact and convenient, this eyepiece is perfect for on-the-go use without sacrificing quality. [ENHANCE YOUR VIEW] Improve the accuracy of your telescope with this precision-made collimation eyepiece for clearer images.