“Backup” is a role, not a law of physics. Flip-up sets can be primary irons on a bare rail, or true backups under an optic. FBUIS-B supports both mechanically; how you zero and which aperture you leave selected should match the role.
| Primary irons | True backup | |
|---|---|---|
| Default state | Usually left up | Usually folded |
| Zero priority | First thing you dial | After optic zero |
| Aperture | Whatever you shoot most | Often large for emergencies |
| Practice | Main live-fire diet | Periodic failure drills |
Buy Ozark Armament Flip Up Iron Sights (FBUIS-B) on Amazon
Product facts from the public Amazon listing for ASIN B01AISP1KW only. No price guarantees. Never invent torque values.