Shield Arms Magazine Catch Premium Mag Release Black Left Hand G43X-PRM-BLK-LH Anodized The Premium S15 Steel Mag Catch for the Glock 43X/48 has been optimized for left or right-handed use specifically and is NOT ambidextrous. Because the catch is not ambidextrous" Shield Arms were able to eliminate hard angles on the bottom of the catch for smoother reloads with their steel S15 magazine. The catch face has been slightly extended vs. their Standard Mag Catch by ~.03"" and there is slightly MORE magazine engagement with this premium catch.