Fab Defense recently released their new polymer back-up sights. The new low-profile sights were designed specifically for the M4/M16/AR-15 rifle as well as their K.P.O.S. conversion kits (seen below), but will work with all 1913 Picatinny rails. No tools are required for windage adjustments on their rear sights as well as for elevation adjustments on their front sights.
The FBS (front) weights in at 25 grams while the RBS (rear) weights in at 30 grams, lighter than the Magpul MBUS Gen II sights. They’ll be available in black, green and tan. The FBS retails at just $34 and the RBS at $38, or you can snag both for $68. Check out Fab-defense.com for more info.