With property of fine insulativity,fine flame tetardant and fine pressure resitant, fine intensity resistant,etc?it use 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 easily.compared with steel pipe,the efficiency can improve by 5times,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?