This is the Sabatti 3 round polymer .223 & .222 magazine for older format Sabatti Rover and Sabatti Tactical rifles, also sold as Mercury 600 series.
While they take 4 at a push, officially it is 3 rounds.
This magazine is for older Sabatti models with serials starting with a single R (Rxxxxx).
Due to variation between older types sometimes a minor adjustment to the round locking hole is required for best fit. Simply open up the upper edge of the locking hole with a few strokes of a round file until the desired lockup is achieved.
Checkout our catch adjustment video from the Sabatti factory.
Manufactured from reinforced polymer.