The Ares 15-45 family of spotting scopes were designed with advanced optical quality and ease of use in mind. Designed with bright razor-sharp imagery and a rugged weatherproof design the Ares is ready for any condition. The interchangeable eyepiece allows you to swap the standard variable power eyepiece with a fixed 22 power eyepiece (sold separately) with a MIL ranging reticle in it for your long range shooting/tactical application. They have Extra-Low Dispersion glass lenses for color resolution and contrast our AFMC (advance fully multi-coatings) and feature BaK4 prisms with the new ESP Dielectric Coating. They bring clarity and brightness within the reach of most enthusiasts. The tough full metal chassis is fog proof and waterproof and filled with Argon gas to prevent internal fogging and better thermal stability. The lenses are then treated externally with Athlon's XPL coating to withstand dirt oil and grime of constant use.