From Ammoland:

The KelTec Sub-2000 Carbine is a 9mm direct blowback carbine that feeds from stagger-column Glock-pattern magazines. You read that right, the KelTec Sub 2000 feeds from Glock magazines – at least, this version does. The model reviewed is designed specifically for Glock 19-pattern mags, meaning it can utilize Glock 19, Glock 17, and any 9mm Glock magazine with a capacity of over 15 rounds. (Or ten rounds in ban states.)