AlstarAstronomical 2"/M48-extension Tube Kit for Cameras and eyepieces - Length 5mm 10mm 20mm 30mm - M48x0.75 on Both Sides

These are well-finished and reasonably sturdy extension tube segments.They thread smoothly and securely onto each other, and to other M48x0.75 thread items such as 2" astro filters.No burs or marring.Nice matte black finish inside and out, low reflectivity.