The Colt CALM S18‑600V is the highest performing acoustic louvre in the range, designed for maximum noise attenuation with airflow. Its 600 mm chevron blade profile, formed by combining two S18‑300 units, achieves Rw (C, Ctr) 31 (‑2, ‑8) when tested to BS EN ISO 10140‑2:2021, while maintaining aerodynamic efficiency (Cv 0.142). With a solid metal appearance front and rear, modular construction, robust galvanised steel, and finish options, it ensures flexibility, durability, and long service life