Fully metal construction and aluminum processing for durable, long-term use. This extension tube helps achieve the correct image scale or precise spacing required for reducers or field flatteners. Features a T2 internal thread and T2 external thread to resolve spacing issues in astrophotography and reduce focusing problems. The required spacing can be achieved by combining multiple extension tubes of varying lengths. Type: Astronomical Telescope T2 Thread Extension Tube Size: M42 x 0.75 Type: Monocular Extension Tube Heights: 3mm, 5mm, 7mm, 10mm, 12mm, 15mm, 20mm, 30mm Why use it? When you cannot reach the correct focal plane with a camera or eyepiece, this extension tube kit solves the issue. Compatible with cameras, eyepieces, and adapters. The M42 x 0.75 threads on both ends provide high versatility. Use to achieve proper image scale or exact spacing for reducers or field flatteners. Required extension length can be achieved by combining different spacers. Color: Black Material: Aluminum Package Contents: 8 x M42 x 0.75 Thread Extension Tubes (3mm, 5mm, 7mm, 10mm, 12mm, 15mm, 20mm, 30mm) Note: Light and display differences may cause slight color variation between the image and the actual item. Measurement allows an error of +/- 1-3 cm.