The development of homogeneous and supported single-site catalysts is one of the most exciting areas in the polyolefin industry. These single-site catalysts produce ethylene a-olefin copolymers with properties that are different from the ones of traditional LLDPE and LDPE polymers. With the aid of Constrained Geometry Catalyst (CGC) metallocene systems, production of ethylene alpha-olefin copolymers, and ethylene polymers having long-chain branches have become possible.