Type: Astronomic telescope M48 threaded extension tube, the height of the extension tube is 3mm, 5mm, 7mm, 10mm, 12mm, 15mm, 20mm and 30mm. | Variable Combination: The required spacing can be achieved by combining several extension rings of different lengths, you can use 1, 2, 3 or 8 extension rings as required. | Aluminum Alloy Material: All metal structure and anodized aluminum process, durable, using this extension tube can obtain the correct image scale or the precise spacing required by the reducer or field flattener. | Eliminate Redundant Light: The design of female thread can eliminate stray light and reflected light, making the image clearer and more perfect. | Type: Astronomic telescope M48 threaded extension tube, the height of the extension tube is 3mm, 5mm, 7mm, 10mm, 12mm, 15mm, 20mm and 30mm.