This description is taken directly from the CCX web site and is an excellent overview of the Chicago Climate Exchange.

Chicago Climate Exchange (CCX) operates North America’s only cap and trade system for all six greenhouse gases, with global affiliates and projects worldwide.

CCX Members are leaders in greenhouse gas (GHG) management and represent all sectors of the global economy, as well as public sector innovators. Reductions achieved through CCX are the only reductions made in North America through a legally binding compliance regime, providing independent, third party verification by the Financial Industry Regulatory Authority (FINRA, formerly NASD). The founder, Chairman and CEO of CCX is economist and financial innovator Dr. Richard L. Sandor, who was named a Hero of the Planet by Time Magazine in 2002 for founding CCX, and in 2007 as the "father of carbon trading."

CCX emitting Members make a voluntary but legally binding commitment to meet annual GHG emission reduction targets. Those who reduce below the targets have surplus allowances to sell or bank; those who emit above the targets comply by purchasing CCX Carbon Financial Instrument® (CFI®) contracts.

CFI Contracts, the CCX Tradable Commodity

The commodity traded on CCX is the CFI contract, each of which represents 100 metric tons of CO2 equivalent. CFI contracts are comprised of Exchange Allowances and Exchange Offsets. Exchange Allowances are issued to emitting Members in accordance with their emission baseline and the CCX Emission Reduction Schedule. Exchange Offsets are generated by qualifying offset projects.