The Razor HD Long Eye Relief Eyepiece from Vortex is designed as a 31mm long eye relief option for the 65mm and 85mm Razor HD spotting scopes. The eyepiece is built with the same High Density (HD) Extra-low Dispersion (ED) glass with anti-reflective XR and ArmorTek scratch-resistant coatings as the Razor HD spotting scopes. It is also Argon-filled and o-ring sealed to be fog and waterproof. The twist-up eyecup makes it comfortable for eye and sunglass wearers. The eyepiece is compatible with only the 65mm and 85mm Razor HD spotting scopes.