Meprolight FRBS 2-Dot Rifle Sight Set - Black - The Mepro FUBS are tritium-enhanced, self-illuminated front and rear back-up sights designed to provide the shooter secondary sights in case the primary optics go down. Mepro FUBS sights are advanced, low-profile, durable, tritium-enhanced auxiliary front and rear back-up sights. The sights quickly fold up or down depending on the shooters' needs. Sight pin elevation is easily and quickly adjusted without tools. Mepro FUBS sights are readily mounted on any 1913 Picatinny rail. Day or night, the tritium makes the Mepro FUBS a viable option. Low Profile Lightweight Manually Adjustable Durable Fiberglass Reinforced Polymer And Medal Spring Based Locking Mechanism Compatible With All MIL-STD 1913 Picatinny Rails