The Chrosziel SD 412 is a high-quality, rotating outer ring designed for use with the Chrosziel 412 series matte box system. This specific component, with a 110mm diameter, serves as the front-most ring that holds square or rectangular filters in place. Its primary function is to allow for the precise rotation of graduated neutral density (ND grad) or polarizing filters, which is essential for cinematographers to align the filter's effect—such as the gradient horizon or polarization angle—with the composition of the shot. The ring features a smooth, geared rotation mechanism and locking screws to secure the filter at the desired orientation once set.

Constructed from durable, lightweight aluminum with a matte black finish to prevent reflections, the SD 412 ring is engineered for precise fit and seamless integration with other Chrosziel 412 components. This accessory is a critical tool for directors of photography and camera assistants working with matte box systems, providing the fine control needed to utilize creative filters effectively on set, thereby enhancing the visual quality and artistic intent of the footage.