This is an OEM Sig Sauer P228 / P229 9mm DLC-coated replacement barrel. You cannot convert a P224 in .40/.357 to 9mm with this barrel
This will not work in a US made P229-1 (E2). If you have a P229-1, you need BBL-229-1-9.
Note that it is not uncommon for barrels to need fitting. We recommend having a gunsmith perform this.