This model was ADCO’s original model so it’s versatility keeps it as a #1 seller. Although designed to help with wider high cap magazines, there is also a groove inside the mag well, front and rear, to align a 1911 style magazine. Years later and more innovations came along we expanded to a complete line as we offer now. If it is not and ADCO, it’s not a Super Thumb. The one that’s guaranteed not to break.