These are the same billet injector seats used in Radium fuel rail kits. They are required when converting an OEM side feed fuel rail to top feed. They simply "pop" into the intake manifold (1 required per injector). They seal to the machined injector counterbore using the included Viton O-ring. The 2 sizes are based on the intake manifold's inside diameter of each injector counterbore. Below are just a few examples of some popular Nissan engines.
30mm = KA24DE S13/S14, SR20DET S13
All 30mm injector seats are bright-dipped black anodized. All 25mm injector seats are bright-dipped green anodized. The injector seats are CNC machined with a common 14mm bore for the lower injector O-ring.
-CNC machined 6061 aluminum
-Bright dipped anodized
-Laser etched logo
Thoroughly clean out any dirt or debris found in the intake manifold injector seat bores. Next, lubricate the Radium injector seat O-rings with engine oil. Press the Radium injector seats down firmly into the intake manifold injector ports until fully seated. If necessary, use a small rubber mallet.