The fiber-optic window on the top of the sight exposes fibers to light from above for better light-gathering efficiency. Machined, all-metal pins protect the fiber in a super-tough microgroove. A built-in level acts as a reference point for more accurate shooting. Fully finished with contoured and radiused edges. Bright, white outline for easy peep alignment. 1.65" sight window. Four .019" pins. Olive Drab finish. Right hand only. Made in USA.