The Helios FSD 100 is a durable flexible duct constructed from aluminium casing. It features a perforated inner surface that holds an approximate 58.5 mm thick mineral wool lining for enhanced sound absorption. The duct has spigots at both ends, allowing connection to other ducts or secure attachment to fans using a pipe clamp connector (BM). Its pressure drop is approximately four times higher than that of comparable rigid ducting.