Rubber-lined duct clamps provide secure support for circular ductwork while reducing vibration and structure-borne noise. The heavy-duty zinc-plated steel clamp includes a welded M10 boss for threaded rod or hanger-bolt installation, while the internal rubber lining cushions the duct and prevents direct metal-to-metal contact. Suitable for residential, commercial and industrial ventilation systems, the clamps are quick to install and are particularly useful where acoustic performance or vibration isolation is important.