Yongnian County billion safety and traffic facilities Co., Ltd. http://ynyajt.com/ 
 Signs special anti-theft bolt connection, including a circular anti-theft nuts, bolts in conjunction with anti-theft nuts, the necking U-shaped connection slot, said bolt nut is square, the U-shaped connection trough internal slide with the. When using the present invention, the U-shaped connecting slot on the back and the connection (such as signs) connection (welding or institution as a whole), the nut into the U-shaped connection slot, screw through the other connection (such as signs of the pole), and then tighten the nut. Nut U-shaped connection groove stuck will not turn, so only with special tools in handling rotating nut can, operation is very convenient.