Welcome to the store! All metal and aluminum process, for long-lasting use. Use this extension tube for correct image scale or the exact distance required for reducers or field flatteners. The extension tube has a T2 internal thread and a T2 external thread to solve distance problems within astrophotography and eliminates a series of focusing problems. The required distance can be achieved by combining multiple extenders of different lengths. Type: Astronomical Telescope T2 Thread Extension Tube SIZE: M42 x 0.75 Type: Monocular Extension Tube Height: 3mm 5mm 7mm 10mm 12mm 15mm 20mm 30mm Why use it? When you can't get to the right plane for focusing with a camera or eyepiece. This extension tube kit solves this problem. You can use this extender with any camera or eyepiece or with various adapters. The M42 x 0.75 threads at both ends are extremely versatile. Use this extender to obtain the correct image scale or for the exact distance required for a reducer or field flattener. You can achieve the required extension length by combining multiple extenders of different lengths. Color: Black Material: Aluminum Package Contents: 8 x M42 x 0.75 Thread Extension Tubes (3/5/7/10/12/15/20/30mm) Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture to be a little different from the real thing. The measurement allowed error is +/- 1-3 cm. Your satisfaction is our top priority. We will provide you with the best service. If you find any problems after receiving the product, such as damage, incorrect quantity, etc., please contact us immediately and we will give you the best solution!