Burris has gone to extremes to engineer the ultimate in high-performance optics ? XTR Xtreme Tactical Riflescopes. Extra-large, ultra-premium lenses produce unsurpassed resolution, clarity, and brightness. Index-matched HiLume multicoating boosts clarity and, enhanced with StormCoat, causes water to bead and shed off for a clearer view when water drops are present. All XTR scope tubes are 30mm, resulting in 25% thicker main tubes and 42% more strength. Double-force coil spring suspension locks the inner tube in place for unfailing accuracy. XTRs also feature side turret-mounted parallax adjustment systems. May or may not include accessories.