with property of fine insulativity,fine flame retardant and fine pressure resistant,fine intensity resistant,etc...it uses the connection way of socket insert,under normal temprature environment,the pipe with diameter lower than 32mm is with our company's special bent which can be inflexible pared with steel pipe,the efficiency can improve by 5 times,the expense of the raw material and the installation can be saved by about 20-30%.recently it is well widely used in construction project,post,communication,electric cable,country project,etc...