Need help to find which scope or red dot would work with my Jing Gong Model-Airsoft M4 S.system V.2 2008 f6614?

I'm planning to buy a Jing Gong Model-Airsoft M4 S.system V.2 2008 f6614 (http://www.import-action.com/gbmom4syaeme.html) but I wanted a scope or red dot sight or something for it. So i decided to want to buy this scope (http://www.airsoftpost.com/trirail-full-metal-scope-with-illuminated-green-rectacle-p-26718.html) but I don't know if it will fit the RAS rails (which someone told me is the same as RIS rails). Can you tell me if this would fit or could you help me find a better scope or something to use, if you can give me the link for it. Thanks