Yes, the product is compatible with the P225 in 9mm.
All P series and SP models use the same dovetail mounting front and rear with the exception of the P250 which has a different rear sight mount configuration (same front sight as others).
However, different Sig Sauer models and calibers come with different sight heights to achieve proper point of impact at 25', depending on the caliber.
9mm and .357 SIG use #8 REAR / #8 FRONT
40 S&W and .45 ACP use #8 REAR / #6 FRONT
Mark H.