Athlon Optics , Argos , Riflescope , 4-20 x 50 Second Focal Plane (SFP) 1" Tube, BDC 600 Reticle , Fully multi-coated lenses gives you better light transmission to bring optimum brightness and true color across the entire light Spectrum Xpl coating gives you an extra protection on the exterior lenses from dirt, oil and scratches Aircraft grade aluminum tube that has exceptional strength and superior mechanical integrity will protect these world class optics no matter what punishment you Throw at it Argon purging gives you better waterproofing and thermal stability Heat treated one piece tube gives the scope extra strength over multi-piece tubes. A one piece tube also is better at keeping moisture out thus keeping your scope fog proof for the life of the product