SISTAN Spring Manufacturing Co
Zar Sistan Spring Company has been established in 2004 with the experiences and technical knowledge of Zar Engineering Company as the biggest manufacturer of different types of spring in Middle East and utilized in 2006. This companu is active in manufacturing different kinds of rail connections in railway. Currently, this company has the capacity of manufacturing 3,000,000 pieces of SKL12 and SKL14 shackles and Omega metal shackle. In addition to these pieces, some other products such as traverse concrete screw and small and big brackets of concrete traverse and different kinds of metal bush are among the products of this company. Moreover, concerning qualitative and manufacturing ranking, it is one of the best manufacturing companies for railway products in Islamic Republic of Iran. 

Different types of spring shackles 
Elastic attraction of forces imposed on the rail and their transfer to transverse is the duty of shackles. The shackles keep the rail permanently on transverse and divided into two groups concerning their installation manner:
   1. Self-locking elastic shackles
   2. Shackles that are connected to traverse by screw
The advantages of spring shackles in railways is safety and reliability, long fatigue life (more than 5 million cycles) and high axial load tolerance and they are easily used for installation or replacement of rail.

Concrete traverse screw 
This screw is used in systems where spring shackle is connected by screw to traverse. This screw is produced based on UIC864-1 standard.

Small and big brackets 
 These pieces are used in concrete traverse and have the role of pre-stressing force transfer. They are made from ST52-3 steel.