The Razor HD 8x42 is argon gas purged and sealed with o-rings to ensure reliable and durable protection against dust, debris, fog and water. It is rubber armored for non-slip and durable protection. It is also equipped with an exceptionally large focusing knob with a pull-push focus that rotates for setting and locking the proper diopter setting. Naturally contoured to perfectly fit your hands, promoting comfort and eliminating user-fatigue Vortex has once again created a winning combination of features.