7. COMMITMENTS AND CONTINGENCIES CONCENTRATION OF CREDIT RISK Zoltek's carbon fiber products are primarily sold to customers in the wind energy and composite industries and its technical fibers are primarily sold to customers in the aerospace industry. Entec Composite Machines  products are primarily sold in the composite industry. The Company performs ongoing credit evaluations and generally requires collateral for significant export sales to new customers. The Company maintains reserves for potential credit losses and such losses have been within management's expectations. In the three months ended December 31, 2012 and 2011, the Company reported aggregate sales of $17.6 million and $18.2 million, respectively, to Vestas Wind Systems, a leading wind turbine manufacturer . In the three months ended December 31, 2011, the Company also reported aggregate sales of $5.7 million to a manufacturer of fabrics for the composite industry, including materials for production of wind turbines. ENVIRONMENTAL The Company's operations generate various hazardous wastes, including gaseous, liquid and solid materials. The operations of the Company's carbon fibers and technical fibers business segments utilize thermal oxidation of various by-product streams designed to comply with applicable laws and regulations. The plants produce air emissions that are regulated and permitted by various environmental authorities. The plants are required to verify by performance tests that certain emission rates are not exceeded. The Company does not believe that compliance by its carbon fibers and technical fibers operations with applicable environmental regulations will have a material adverse effect upon the Company's future capital expenditure requirements, results of operations or competitive position. There can be no assurance, however, as to the effect of interpretation of current laws or future changes in federal, state or international environmental laws or regulations on the business segment's results of operations or financial conditio