The "Soundcraft Expression 1 Dust C" refers to a custom-fit protective cover for the Soundcraft Si Expression 1 digital mixer. This accessory is designed to shield the console from environmental contaminants, such as dust, grime, spills, and scratches, which can harm the sensitive components and faders of the console over time. These covers are typically made from durable, long-lasting, and anti-static fabrics, like nylon with a PVC lining, and are machine-sewn for durability. They are designed with an open bottom, allowing them to easily slip over the console's top and be stored when not in use.