Monstrum Tactical 3-9x40 Rifle Scope with Illuminated BDC Reticle High optical clarity at 3 to 9 times magnification, 40mm objective diameter Glass BDC (bullet drop compensation) reticle for on-the-fly range estimation and long distance targeting Dial controlled reticle illumination in both red and green with multiple brightness intensities, for clean sight picture regardless of lighting or environment Integrated rail mount fastens securely to any flat top Weaver or Picatinny rail equipped rifle