The factory clutch line in your RX7 is reinforced rubber. This line expands from hydraulic pressure and thus pressure is lost instead ofaffecting the clutch slave piston. This clutch line is custom made just for the FD RX7, it is not a clutch line that happens to fit. A CorkSport clutch Line is recommended for any aftermarket clutch, but is also a great upgrade for a stock setup.

The Teflon hose is covered with braided stainless steel to resist expansion better than the OEM clutch line. Every CorkSport clutch line comes with a protective coating to keep grease and grime off the stainless braided exterior. 

The line comes in a clear coating.

Take a look at our technical article that explains the benefits of the stainless braided lines here.