The Helios FM 400 flexible sleeve serves as a connector to reduce vibration transmission between fans and duct systems. Engineered for use with compatible FR flanges (sold separately) fitted on fan spigots, it ensures smoother operation by minimizing vibration transfer. Supplied in pairs with durable worm screw clamping bands, this flexible sleeve is available in sizes ranging from 100mm to 710mm, providing reliable installation and performance in ventilation applications.