TRUGLO Brite-Site Tritium Sight, Fits S&W M&P, Green TG-TG231MP When the lights go out" your sidearm doesn't need to be left in the dark. Tritium night sights transition from standard white dot sights during the daylight" to glowing green dots in the dark. Tritium does not need batteries and does not need to be charged with light - it simply glows!