Fully metal construction with anodized aluminum, durable for long-term use. Use this extension tube to achieve the correct image scale or precise spacing required for reducers or field flatteners. The extension tube features T2 internal and external threads, designed to solve spacing issues in astrophotography and eliminate focusing problems. Required spacing can be achieved by combining multiple extension tubes of varying lengths. Type: Astronomical Telescope T2 Thread Extension Tube Thread Standard: M42 x 0.75 Extension Tube Lengths: 3 mm, 5 mm, 7 mm, 10 mm, 12 mm, 15 mm, 20 mm, 30 mm Use this extension tube when the camera or eyepiece cannot reach the optimal focal plane. It is compatible with various cameras, eyepieces, and adapters. The M42 x 0.75 threads on both ends ensure broad compatibility. Use this extender to obtain the correct image scale or exact spacing needed for reducers or field flatteners. Customize total extension length by stacking multiple tubes of different lengths. Color: Black Material: Aluminum Package Contents: 8 x M42 x 0.75 Thread Extension Tubes (3 mm, 5 mm, 7 mm, 10 mm, 12 mm, 15 mm, 20 mm, 30 mm) Note: Color may vary slightly due to lighting and display differences. Measurement tolerance: ±1–3 mm.