These hurricane board-up clips are constructed of stamped steel and come unfinished. They are designed for fast and secure board-ups over windows on brick, wood and stucco surroundings that are sufficiently recessed in from the exterior finished surface, with 90 degree right angle surfaces adjacent to the windows for them to work. These clips help provide swift shielding of windows from high winds and dangerous airborne debris. Installation instructions are provided for use with 1/2 inch thick plywood, to include mounting and removal for storage and future use. Kindly refer to the wind speed chart for proper count and spacing of clips to be used, based on wind speed and overall window sizes. The chart covers window sizes ranging from 24 to 96-inch Wide, and for wind speeds up to 110-150mph., all depending on overall window size opening. To install you push the plywood with clips into your window frame. To remove the panels grasp the tension legs with a gloved finger and pull toward you to release the tension. If needed, you can use a pry bar if the tension is too tight.