These are the same machined aluminum injector seats used in Radium fuel rail kits. They are required when converting an OEM side feed injector to a top feed injector that uses a 14mm lower O-ring. They simply "pop" into the intake manifold (1 required per injector). They seal to the machined injector counterbore using the included FKM 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
25mm = RB25DET, SR20DET S14/S15, SR20VE FWD
All 30mm injector seats are black anodized. All 25mm injector seats (shown below) are Radium 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.