Replacement magazine spring. Some fitting may be required.
140mm will work in factory high capacity magazines and with up to +4 extensions, in 38 Super, 40 S&W and 45 ACP. 140mm is 11 coils, the factory spring is 10 coils. The 140mm will need to be shortened is when used in factory, flat bottom magazines with shortened grip frames like the P13. Springs will work with 9mm Luger models.