The FRBS and illuminated flip up sights by Meprolight are designed to be bright enough to see in low light situations, but not too bright that it impacts your sight picture. They feature a durable construction of metal, polymer, and fiberglass. The dot configuration is composed of 4 rear dots and one Hyper-Bright front sight. In addition, the FRBS sights can be adjusted without tools, and lay flat and out of the way until they’re needed. Features of the FRBS Flip Up Sights: Can be adjusted without tools Available in black or FDEDurable construction Meprolight USA Meprolight FRBS M4D Hyper-Bright Orange Front/4-Dot Green Rear Tritium Illum Flip Backup Sight Set 403240