This is a Marbles Arms tang sight (aka Peep Sight) Winchester and Browning model 71 (will not fit the Browning carbine) . It comes with 3 different sight apertures (1/2 inch diameter with .055 hole; 1/2 inch diameter with .102 hole; 3/4 inch diameter with .032 hole). Hole spacing on the base of the sight is .375, and the height adjustment is 2.135 inches to 2.470 inches, with a 21 degree angle. Mounting screws are NOT INCLUDED with the tang sight, so if you need those screws they can be purchased in the option box below. If you have a long tang model please see st9817 or st9822