Explore Scientific Extension Ring Set M48x0.75 - 5 pieces (30, 20, 15, 10 and 5 mm)Explore Scientific Extension Ring Set M48x0. 75 5 pieces (30, 20, 15, 10 and 5 mm) This set includes five extension tubes with lengths of 30, 20, 15, 10, and 5 mm, each featuring an M48x0. 75 mm thread connection, also known as the large T2 photo thread or 2 inch filter thread. These tubes are designed to help adjust the distance between your camera and the telescopes focal plane or accessories like correctors and field flatteners. With both internal