I have a Friend and local gunsmith near me that started making
his own STI Mag catches they are right handed only..
ie: the button has been moved to the right side , to help
insure that you get your trigger finger off the trigger and on the release.
here is his website take a look and let him know that Jerry Sent ya. Mag Catch
BTW the caspian gun that you see in the pic is Mine with the first