I just purchased 2 ProMag 13 round magazines for my P228. I have not shot with them yet, but I was surprised when I loaded the first mag it held 15 rounds of 9mm. I thought I got the wrong mag, I loaded the second and found it too held 15 rounds of 9mm. They both fit the Sig perfectly and manually feed without a problem. I'll know more tomorrow after I get a chance to shoot with thme.