Drop in anchor is generally used to install partitions or ceiling. The burst screw is made of carbon steel and has an electrogalvanized finish. The material is more resistant to corrosion, moisture and rust. The package is white box + kraft paper box + wooden tray.the size is M6,M8,M10,M12,M14,M16,M20.It usually has the quality level according the weight for 1000pcs .so we can buy different qulity by my demand .we can accept customer request .just like the double knurl,and flange drop in anchor and plain drop in anchor .the thread has different type ,just like GB ANSI AND GB .