The Helios FSD 315 is a durable flexible duct made from aluminium casing. Its perforated inner surface securely holds a mineral wool lining of approximately 58.5 mm thickness, providing effective noise reduction. The duct is equipped with spigots on both ends, allowing easy connection to other ducts or attachment to fans using a pipe clamp connector (BM). This duct experiences a pressure drop about four times higher than that of standard rigid ducting.