point of HRB and grade. H, R, and B are the first letters of hot-rolled, Ribbed, and Bars respectively. Rebar can be divided into
three categories according to strength: HRB300E, HRB400E, HRB500E, HRB600E, etc.
22mm, 25mm, 28mm, 32mm, 36mm, 40mm, and so on. Generally, the fixed length of rebar is 9m and 12m, among which 9m long thread is
mainly used for normal road construction and 12m long thread is mainly used for bridge construction.