This Filter Stack Cap consists of a set of top and bottom durable metal caps to fit filters with different diameters. They will protect the filters from dust, scratches and fingerprints while not in use. Simply screw your filters together then screw the stack caps on the top and bottom. Additionally, this enables a more organized, streamlined system for storing and carrying your filters. Made of aluminum alloy, the filter cap is slim and exquisite. That's to say, it is easy to carry and takes up a little space. Words are carved on the surface of the top cap by laser carving technology.