For the G1 STI 2011 grips. Mag catch is IDPA .190 length , drilled, and tapped for 4-40. Machined to specs not cast or mimed. Positively locks the magazine in and engineered to prevent pushing the button in too far. If you are upgrading to an Extreme Shooters textured G1 grip on a Staccato frame, you will need to use this mag catch to complete the G1 conversion. This mag catch will not fit the new Staccato G2 grips.