For a SAR-3, you have two main choices of mags. Best are the "Weigar" steel mags. CDNN had them last time I looked, which was a while ago.
Your other option is Bakelite mags, which are really 5.45X39 mags. If you don't replace the follower with a "Robarms" follower (From Robinson Arms) and file the feed lips a little (to look like a Weigar Mag) you won't have good reliability with those mags. And that what' Century was shipping with them for a while. Looks like that's what you have in your pic.
I got my SAR-3 when they first came out. It has been utterly reliable. When cold, it shoots 2 MOA, but when warm, it opens up to 4-5MOA. Love mine.