76MM Newton Reflector Astronomical Telescope Reflector Objective Set Primary Secondary Mirror DIY Telescope LensesSpecifications:D76F300+20mmSpherical primary mirrorMaterial: K9 Optical glassDiameter: 78mmFocal length: 300mmThickness: About 11mmNet weight:120g.Coating: Aluminum coating and protective filmSecondary mirror: Minor axis (short side diameter) 20mmD76F360+20mmSpherical primary mirrorMaterial: K9 Optical glassDiameter: 78mmFocal length: 360mmThickness: About 11mm Net weight:120g.Coating: Aluminum coating and protective filmSecondary mirror: Minor axis (short side diameter) 20mmD76F700+20mmSpherical primary mirrorMaterial: K9 Optical glassDiameter: 78mmFocal length: 700mmThickness: About 11mm Net weight:120g.Coating: Aluminum coating and protective filmSecondary mirror: Minor axis (short side diameter) 20mmD76F900+20mmSpherical primary mirrorMaterial: K9 Optical glassDiameter: 78mmFocal length: 900mmThickness: About 11mm Net weight:120g.Coating: Aluminum coating and protective filmSecondary mirror: Minor axis (short side diameter) 20mmNote:Please allow 01 inch error due to manual measurement.Thanks for your understanding.Note:1. The real color of the item may be slightly different from the pictures shown on website caused by many factors such as brightness of your monitor and light brightness.2. Please allow slight manual measurement deviation for the data.