This filter drawer features a one-piece molding design, preventing light leakage and a magnetic closure. Compared to traditional screw-operated methods, the magnetic attraction is stronger, making installation and use more convenient. CNC one-piece molding and advanced processing technology ensure quality, providing more accurate and stable imaging results; you can use it with confidence. The filter drawer is 21mm thick, a thickness related to the back focal length. The back focal length affects image quality and limits accessory usage and optical path length. A locking screw is located on the side of the filter drawer. The locking function helps adjust tension, eliminates gaps, and provides double protection. Filter Drawer Specifications Using with a Telescope: Connect the telescope to the focal length reducer and filter drawer; then connect the adapter to the camera. This filter drawer is compatible with the FD-M42M. Color: Black Material: Aluminum Alloy Package Contents: 1 * filter drawer Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.