Preassembled for quick and easy installtion,can be used in thin sections of concrete of solid masonry. Head styles for every application. The test values listed beneath were obtained using 200-250kgs/cm concrete(no aggregate). A safe working load should not exceed 25%of stated value. Usage:First, we need to use electric drill to drill specific size of the hole; Second, putting expand plug in the hole; Finally, using a screwdriver to tighten screw into the expansion tube until the specified location