Getting product code

Hello, i would like to get the Nintendo product ID, Sony product code, ... of games. ( like we can see there : http://www.giantbomb.com/metroid/3030-21761/releases/ ). But I can't find how to request the API to get this info.

I tried : http://www.giantbomb.com/api/release/3050-74971/?api_key=[MY_KEY]&format=json but i don't get them. Could someone help me ?

Thanks :).

I get the product code value(UPC/A) : "0 45496 63034 8" for Metroid USA the Product code type, but not the ID I want.

I don't understand why i don't get this field. Is it possible to get this info with the API ?