Specification AgeRangeDescription : adult Brand : LingoFoto BulletPoint1 : Includes 8 different lengths - 3mm 5mm 7mm 10mm 12mm 15mm 20mm 30mm. The required spacing can be achieved by combining several extenders of differing lengths, you can use 1 pc, 2 pc, 3 pc of the extension rings as you like BulletPoint2 : The 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.Use this extension tube for getting the correct image scale or the exact spacing required for reducers or field flatteners BulletPoint3 : Male thread - M42x0.75. Female thread - M42x0.75, eliminates a range of focusing problems BulletPoint4 : Fully metal construction and anodizing aluminum process, durable for long time use BulletPoint5 : 3mm/5mm/7mm/10mm/12mm/15mm/20mm/30mm M42*0.75 Extension Tube*1 Color : As Shown ExternallyAssignedProductIdentifier : 7671530130197 IncludedComponents : T2-Extension Tube*1 ItemName : LingoFoto T2-Extension Tube for Cameras Eyepieces M42 Extension Tube-Length 3mm/5mm/7mm/10mm/12mm/15mm/20mm/30mm M42x0.75 Thread on Both Sides Tube for Astronomical Telescope Camera Extended (5MM) ItemPackageDimensions_Height : 2.36 inches ItemPackageDimensions_Length : 2.36 inches ItemPackageDimensions_Width : 2.36 inches ItemPackageQuantity : 1 ItemTypeKeyword : camera-lens-extension-tubes Manufacturer : LingoFoto ModelName : Adapter Rings ModelNumber : PTEUL15HYGK094035 NumberOfBoxes : 1 NumberOfItems : 1 NumberOfLithiumMetalCells : 1 PartNumber : TA3150-YJY ProductDescription : Description: 1. The function of the extension cylinder is to increase the distance between the lens and the imaging screen. It has a T2 interior thread and a T2 exterior thread for solving spacing problems in astrophotography and eliminates a range of focusing problems. 2. Fully metal construction and anodizing aluminum process, durable for long time use. 3. Use this extension tube for getting the correct image scale or the exact spacing required for reducers or field flatteners. 4. Includes 8 different lengths - 3mm 5mm 7mm 10mm 12mm 15mm 20mm 30mm. The required spacing can be achieved by combining several extenders of differing lengths, you can use 1 pc, 2 pc, 3 pc of the extension rings as you like