This replacement magazine is a factory original from Ruger. Factory replacement parts are manufactured to the exact same specifications and tolerances and use the same manufacturing materials as the original parts which guarantees excellent fit and reliable operation. Keeping a few extra factory magazines around is never a bad idea; extra magazines save loading time at the range and also serve as a backup for those days when you simply cannot remember where you put your primary magazine. Note: These magazines are only compatible with Ruger American rifles that were made to accept the Ruger Rotary magazines. New manufactured American rifles in .223, 5.56, 300 Blackout accept AR-15 style magazines.