This is a screw-type front sight with five interchangeable colors. You can replace the fiber optic front sight from the guide integrated with the screw and secure it with the stopper rings (5 included). The screw diameter is 2.6mm, which is used in shotguns such as Beretta, Miroku, and Nikko. I bought it for a Benelli, but it's practically new, having only been attached to the screw hole once. The colors are "Red, Green, Yellow, Blue, and White." Front Sight Bead Diameter → 3.8mm (thin) / 5mm (thick) Front Sight Length → 15mm