The D4 satellites were designed to appeal to the style-of-life customer who prefers audiophile performance. The basic design and performance parameters belong to Era, while a large part of the engineering should be attributed to Michael Kelly. The drivers were custom designed by Michael to ensure a very high level of performance at a reasonable price. When you couple terrific fidelity with a heavily fortified cabinet wrapped in exotic wood veneers; the Era speakers represent an enormous value.