FRBS Offset/Flip-Up SightsWhether for competition, duty or defense, optical system rule the day in terms of shooter preference. But optics do fail. To keep your carbine in the competition, the FAB Defense FRBS Offset kit provides an affordable backup sighting system. The Front Rear Backup Sight (FRBS) offers insurance for when an optic goes down. Mounted at a 45 degree, the system engages target for fast CQB work with a primary optic serving longer range work. Many competitors