BARSKA 6-20x50 IR, Tactical Mil-Dot Side Parallax Riflescope 6-20x variable magnification with large 50mm objective lens in a 100% waterproof and fogproof extra rigid shockproof construction Fully multi-coated optics with Illuminated Mil-Dot glass etched reticles with first focal plane Allows precision adjustment with a side parallax adjustments in a turret-mounted focus knob BARSKA's Accu-lock system utilizes a coil-spring positioned within the scope to securely lock the inner tube Bonus accessories includes a set of mounting rings. Focal plane which the reticle expands as the magnification increases creating dead-on accuracy.