The "OPEC Basket" consisting of crude Oil from the following countries and names: 

"Arab Light", which is Crude Oil from Saudi Arabia. "Bonny Light",  which is crude oil from Nigeria. "Fateh", which is crude oil from Dubai, "Isthmus" from Mexico (which is non-OPEC), "Minas" Indonesia. "Saharan Blend"  which is crude oil from Algeria. "Tia Juana Light" from Venezuela.

OPEC traditionally try to keep the crude oil price of the Opec Basket between upper and lower price limits, by increasing and decreasing oil production. This makes the measure important for oil market trading analysts. The "OPEC Basket", which is a a mixture of both light and heavy crudes, is heavier than both Brent and WTI crude oils.