1. By using multilayer flat tumbler construction, latch bolt solid core is steel, and the interface it touches with the door is arc shape, and also the direction can be changed freely, which make it is easy to installation and safe to use!　　　　　　　　　　　　　　　　　　　　   2. The thickness of the galvanized plate is 2.0mm, which is much more stiffness than the 1.2mm thickness of ordinarily lock, and strengthen the lock capability of safety, pick-proof and anti technical opened.