Eyepiece parfocalizing rings allow you to set the focus of multiple eyepieces accurately so that you can change eyepieces rapidly without refocusing. The ring mounts on the barrel of the accessory (eyepiece, camera, etc.) to set the focus point. The slim rings allow a close fit to the eyepiece barrel. Each ring is supplied with a fitting allen key. The rings are precision-manufactured from aluminum. Available for 1.25" and 2" eyepieces.