aluminum alloy sunshade tube. reduce sun glare on your objective lens. corrosion-resistant. screws on and off with ease. Varies sizes as below; let me know which number/s you want. 1) 42.8mm thread outside diameter x 45mm long 2) 42.8mm thread outside diameter x 50mm long 3) 56.8mm thread outside diameter x 75mm long Sunshade outside thread diameter will match the inside diameter of the threaded part of the objective lens.