FiloSeal+HD is a duct sealing system that uses hexagonal tubes and a flexible sealant to provide a strong support structure for sealing cable configurations in ducts. The sealant, MD+, is a one-component, silicone-based sealant that is easily applied and cures with air. It adheres well to common building materials and provides high levels of gas and water tightness. The unique hexagonal tube design allows for simple positioning and separation of cables while providing backing for the sealant.