Seinfeld: "What's Will These Mags?"

[HMMurdock]

I've seen the new style AK's (AK-103, etc) that are chambered in the 7.62x39mm caliber but have black plastic, smooth '74-like magazines. What's up with that?

Is there any benefit to these new magazines versus the classic metal ribbed ones and, more importantly-- where can I purchase some at?

Thanks

TRL