Strike Industries Extended Magazine Plate, Fits Glock 17/22 Magazine, +5 Capacity, Black SI-EMP-AL-G17-BK The Strike Industries Aluminum Extended Magazine Plate for GLOCK G17 (9mm) / G22 (.40 cal) was designed to provide smoother magazine reloading through a slow drag / no snag design while maintaining maximum magazine capacity. Machined from 6061-T6 aluminum" this Extended Magazine Plate (EMP) adds plus 5 9mm or plus 4 .40 cal rounds to compatible OEM double stack GLOCK magazines.