["Product Description:\n\nFully metal construction and anodizing aluminum process, durable for long for time use.\nUse this extension tube for getting the correct for image scale or the exact spacing required for reducers or field flatteners.\nThe extension tube has a T2 interior thread and a T2 exterior thread for solving spacing problems in astrophotography and eliminates a range of focusing problems.\nThe required spacing can be achieved by combining several extenders of differing lengths.\nType: Astronomical Telescope T2 thread Extension Tube\nExtension Tube Height: 3mm 5mm 7mm 10mm 12mm 15mm 20mm 30mm\nMale thread: M48*0.75mm\nFemale thread: M48*0.75mm\nColor: Black\n\nPlease Note: This Combi are M48 (48mm) thread caliber, not M42 thread caliber\n\nDue to different production batches, the two paint color on the surface(Matte black; shiny black) are shipped randomly.\n\nNote:\nPlease allow 0-2mm error due to manual measurement. pls make sure you do not mind before you bid.\nDue to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!\nIf you really care about these details, pls DO NOT order.\n\nPackage Include:Optional\n1 x Extension Tube Kits（Size can be selected）\nOr \n1 x set of 8 M48 Extension Tube Kits (3/5/7/10/12/15/20/30mm)"]