This replacement magazine spring fits factory original Sig Sauer magazines of Italian origin. Using factory replacement parts guarantees excellent fit and reliable operation. This particular spring fits the following models:SP2340 357 Sig, 40 S&W 10-Round
SP2340 9mm Luger 15-Round
Sig Sauer magazines, magazine springs, and magazine bodies are either manufactured in Italy or Germany. German made magazines have a zipper style weld while Italian magazines have a flush fit as the weld is made on the inside of the magazine body. A German magazine body will only accept a German spring, likewise an Italian magazine body will only accept an Italian spring.