A folding rear sight includes a base member and a spring-loaded sight housing that deploys into an operational position with a simple release lever. The sight includes two separate dual-purpose aiming elements, one fixed, and one that rotates between an inactive position and an active position in front of the fixed element. The top aiming end of the fixed aiming element includes a large diameter close quarter battle (CQB) aperture and an vertically extending sighting notch configured and arranged above the large CQB aperture. The top aiming end of the rotatable aiming element includes a smaller, long-range sighting aperture and an elongated vertically extending sighting notch configured and arranged above the smaller sighting aperture. The dual-purpose aiming elements provide standard aperture sights for situations where the soldier has reasonable time to aim the weapon. The notched sights above the apertures provide a larger, open sighting window, which is easier to align in stressful close combat situations, as well as long range sighting.