Designed and built in the US of A. AutoLock feature requires you to push a locking lever to disengage the mount, so even if you snag the release lever on something, your sight won't accidentally come off. Everything is compact, flush and no sharp corners. The AD-B2 base is so versatile that you only need to switch spacers to go from ACOG to T-1/H-1 to CompM4; from low 1/3 co-witness to dead center co-witness. Outstanding workmanship. Best of all, the American Defense mounts seem to be less expensive than the others. Highly recommended.