Explore Scientific 34mm 68 degree Series Argon-Purged Waterproof Eyepiece. This eyepiece by the professionals at Explore Scientific uses advanced computer design combinations of low dispersion and high refractive index optical glasses and durable multilayer deposition coatings. The Explore Scientific 34mm 68 Series Hyper-Wide Argon-Purged Eyepiece is impervious to internal fogging and contaminants such as fungus growing in between the lens elements. The Explore Scientific 34mm 68 Series Ultra-Wide Argon-Purged Eyepiece gives you the eye comfort to observe at the visual limits of the telescope. Specifications for Explore Scientific 34mm 68 Series Ultra-Wide Argon-Purged Waterproof Eyepiece: Focal Length: 34mm Length: 100.8mm Width: 69.6mm Weight: 24.1oz; 685g Barrel Size: 2.00" Eye Relief: 26.4mm Field Stop Diameter: 38.6mm Package Contents: Explore Scientific 34mm 68 Degree Series Argon-Purged Waterproof Eyepiece 68 Series 34mm Argon-Purged Waterproof Eyepiece; 2.0-inch O.D.