The 40NFR is a very high efficiency, (86dB 1watt / 1 meter) 4-inch full range speaker with linear frequency response characteristics and high power handling capability while generating low harmonic distortion artifacts. The 40NFR uses a unique exponential cone, made off very lightweight glass-carbon fiber woven fabric, along with a NBR single roll geometry surround. The combination provides remarkable strength, high efficiency and sustained output under extreme conditions. Magnetic circuit designREDCATT engineers have developed neodymium based magnetic circuit, capable of delivering the highest level of performance, providing a consistent,high integrity magnetic flux gap, low distortion characteristic. The magnetic circuit design is optimized to generate the minimum amount of flux modulation, providing exceptional stability. The compact size of the magnetic circuit ensures the speaker can fit in tight space of modern audio product designs.