Features: Durable not easy to rust.This is the metal plate attached to the underside of the base. Helps to strengthen the bottom of the for tour pack and increase its service life. Enhanced secure installation support on mounting luggage racks. Easy installation: Mount directly to the bottom of the mounting luggage rack with pre-drilled holes in line with the for tour pack holes. Item name: universal luggage box for case trunk tail box quick release base. No instructions available ,easy to install back on original position. Specifications: Material:PP Size:Approx.18.5x17.5cm/7.28x6.88inch Size:Approx.23.5x25.5cm/9.25x10.03inch Color:Black Note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thanks for your understandings. Package includes: 1 Set Tail Box Fixing Plate