FAB Defense FXFRBS Front/Rear Folding Back-Up Sights – Dual Aperture Rear Sight

The FAB Defense FXFRBS Front/Rear Folding Back-Up Sight set gives AR-15, M16, and M4 shooters a reliable, low-profile aiming solution that folds out of the way when not needed and pops right back up for fast target acquisition. Whether used as a primary sighting system or as a back-up to a red dot or scope, this set is built to perform when it counts.

Both the front (FBS) and rear (RBS) sights mount directly to any standard 1913 Picatinny rail, making installation simple on virtually any AR-pattern rifle. The rear sight features dual apertures: a 3mm aperture for longer eye relief, low-light shooting, and faster target acquisition, and a 1.5mm aperture for shorter eye relief and greater precision. Each aperture is instantly selectable to match changing conditions. The ergonomic angel-wing-shaped shrouds on both sights help center the sight picture and protect the sight posts from impact, and the construction combines durable black polymer with metal components for long-term reliability.

Key Specifications

• Style: Folding Front and Rear Back-Up Sights
• Mounting: Fits any standard 1913 Picatinny rail
• Rear Sight Apertures: 3mm and 1.5mm dual aperture, instantly selectable
• Front Sight Design: Ergonomic angel-wing-shaped shroud for centered sight picture
• Construction: Black polymer and metal
• Compatibility: AR-15, M16, M4 platforms
• Function: Usable as primary or back-up sighting system
• Weight: 0.225 lbs

Shooters who want a dependable, low-profile back-up sight set that adapts to different lighting and range conditions will appreciate the dual-aperture design. FAB Defense FXFRBS Front/Rear Folding Back-Up Sights for sale at Loftus Firearms.