An ORIGINAL Lyman tang sight (aka Peep Sight)for all calibers in the Winchester 1905, 1907, 1910. Tang screw Hole spacing on the base of the sight is 1.000 inches outside and 0.800 screw-center to screw-center. Sight adjustment is 1.680 inches to 2.015 inches, with an 18 degree angle. This ORIGINAL tang sight has a "SL" clearly stamped on the bottom.