TRUGLO Brite-Site, Fiber Optic, Sight, Low, Fits Glk 9/40SW/357Sig TG-TG131G1 TRUGLO fiber optics absorb and channel the existing ambient light to produce bright and precise aiming points. TRUGLO sights are the brightest aiming points in the industry. They give the shooter greater sight contrast for quicker sight alignment" better target acquisition and a clearer sight picture under all shooting conditions. TRUGLO fiber optics are ideal for dusk and dawn or other low light hunting conditions.