2x Hydroponic Acoustic Fan Silencer Fox Silencers 100mm / 4″ Inch x 1m Long (other sizes available please check our other items for sale) Double Wall Thickness – 50mm Insulation Silencers are applied for noise absorption during the operation of the fan. The silencer is attached to the fan to reduce the noise level in the air duct. The Fox Silencer is made of micro-perforated aluminium foil and laminated with polyether film. Reinforced steel wire and outer polyethylene sleeve makes the fox silencer more durable Please see our shop for more hydroponic / ventilation products! Free 1st Class Delivery!