These are the same machined aluminium injector seats used in Radium fuel rail kits for Subarus. They are required when converting an OEM side feed fuel rail to top feed. They simply “pop” into the OEM side feed injectors bores on the intake manifold or TGV housings. They seal to the machined injector counterbore using the included Viton O-ring. Sold in sets of 4.
The 26mm injector seats are for early Subaru engines. They are black anodised.