The LED-based, mercury-free troffer lights designed and manufactured by Cree Inc. now meet standards set by the DesignLight Consortium. (A troffer lamp uses an inverted trough as support and as a reflector.) The DLC consists of utility companies and regional energy-efficiency organizations that certify the quality and performance of energy-efficient lighting. Its list of qualified products is used by utilities to evaluate and choose solid-state lighting fixtures not covered by Energy Star standards, and this included LED-based troffers. Some electric companies even offer rebates to customers who choose DLC-approved equipment.