On this page, you are looking at the Subaru STI 1.3 BAR Radiator Cap.
Here are the details:
Higher pressure than stock
Raising the pressure in the cooling system raises the boiling temperature to hold in more heat
NOTE: Some models have 2 caps one being in the radiator and the other being in the expansion tank-replace both caps to improve cooling efficiency
NOTE: Will not fit BRZ/FR-S models