Material Zinc Steel Closure Type Tee, Insert Exterior Finish Zinc Metal Type Carbon Steel, Zinc Finish Type Finish: Size M8*20mm About This Item Excellent Quality: These nuts are made from high quality zinc plated carbon steel. quality that provides strength and good corrosion resistance in many environments. Easy to Use: These versatile threaded nuts allow you to use them easily, easy to use. Features: Insert nuts are advantageous over barrel nuts and T-nuts because they can be installed from one side of the workpiece. Matching kit: There are 6 different sizes of insert nuts. nuts Note: The pre-drilled hole should be as deep as the length of the insert nut plus any part of the bolt that can be screwed past the end of the nut in the workpiece