Yongnian County billion safety and traffic facilities Co., Ltd. http://ynyajt.com/ 
 Expansion screws of fixed but the use of pull-shaped slope to promote the expansion of the friction bond strength, to achieve the fixed effect. Screw a thread, a vertebral degrees. Wrapped in a metal, metal cylinder half the number of incisions, with thiophene into the hole in the wall to lay the, and then lock nut Nut screw pull it out, the the vertebral degree into the tin cylinder, metal cylinder up to open, so firmly fixed on the wall, are generally used for fencing, awning, air conditioning and other fastening material such as cement, brick. It fixed is not very reliable, if the load is larger vibration may occur loose, and is not recommended for the installation of ceiling fans. 
 The expansion screw is stainless steel expansion screw and plastic expansion screw points, specific uses are not the same. 
 Will tighten the expansion bolt tail has a big head, bolt outside a circle slightly larger than the bolt diameter pipes, the rear part of Jidao opening, when the bolt is tightened, the bulk of the tail was taken to opening the tube inside, red tube big, to achieve the purpose of expansion, and then bolt in the floor or wall, to achieve the purpose of rooting