"The Weaver 3-15x50 Side Focus Tactical Riflescope with EMDR Illuminated Reticle has been specially engineered for tactical applications. It has been manufactured to the strictest tolerances in order to perform in the harshest environments. The 3-15x50 Tactical riflescope is waterproof, fogproof and shockproof. It has a 30mm, single piece tube construction. This riflescope is endowed with a Mil-Dot reticle and has fully multicoated lenses that contribute to the brightness and contrast of the optics. Locating the reticle in the first focal plane allows the size of the pattern to increase as the magnification is increased. This is preferred by many tactical groups for use as a point of aim and as a means of measurement.The side focus feature allows parallax adjustment to keep the reticle and target aligned regardless of the shooters head position. An extra-hard coating on the exterior lens surfaces protects the optics from the scratches and abrasions that all too often occur in the rough and tumble world of tactical endeavors. With a comfortable eye relief of approximately 4 inches and a 1/4 MOA click value for the windage and elevation turret adjustments, this riflescope is provisioned with all the features required for serious tactical work. This is a serious glass for serious situations.|Powerful 15x magnification|Fully multi-coated lenses with extra hard coating on exterior lenses|First focal plane reticles|Waterproof / fogproof / shockproof|Side focus parallax adjustment|Reset-to-zero turrets (no caps to lose)|Argon purged tubes to eliminate internal fogging|One-piece construction|30mm tubes"