Exclusive to Focal and made in France, the Slatefiber membrane is made from recycled carbon fiber and thermoplastic polymer. In their quest for perfection and as specialists in loudspeaker membranes, our engineers have chosen to use non-woven carbon fibers in this case.es in the same direction to achieve even greater rigidity, damping and lightness, the "essentials" of a good loudspeaker. Renowned for its dynamic, rich and balanced sound reproduction, this membrane has proved its worth on numerous products for the home, for professionals in recording studios, and also for listening in the car.