M12 lens mount to hold interchangeable lenses with different back focal length; Come in 18mm and 20mm hole spacing for different board cameras; 8 styles with different heights in plastic and metal carefully labelled and sorted; Compatible with Arducam Lens Board for Raspberry Pi (Arducam B0031) and Arducam M12 len set (LK001/LK002); Screws also included for you to replace the lens mount. Feel free to contact Arducam if you need our further help