These are the Tein H Tech lowering springs. These aprticular springs are specific for the 2015+ Subaru WRX/STI Sedan. The Tein H Techs were designed to improve both looks and handling. These were designed and tested in North America to be used with OEM or aftermarket shocks.

Furthermore, these springs feature:

Chrome Vanadium construction
Progressive spring rate design
Gold powder coated finish
1-year manufactures defect and sag warranty which covers over 5mm sag, breakage, deformity, and noise. Does not cover powder coating and finish.