Rockfon® Koral™ offers an NRC of 0.85, due to the inherent performance benefits of its stone wool core. Rockfon® Koral™ is cleanable, features low embodied carbon with GWP as low as 0.190 kg CO2 – eq/ft2 / 2.04 kg CO2 – eq/m2, and sag, mold and mildew resistance.