Rebar A1 is referred to a soft or plain rebar, often without tread, and the amount of carbon used in A1 is lower than other types of rebar.

The rebar is semi-rigid and is classified in the S340 category. Its appearance is a longitudinal axis and a spiral series relative to the longitudinal axis.

The rebar is hard with twisted tread and the rebar is with the spiral tread. It is in the semi-hard category in terms of hardness.

The ribbed bar or compound tread baris called the A4 bar. It has a longer durability and strength than A1-A2-A3 rebars.