These fuel tubing kits are commonly used for plumbing in-tank submerged fuel pumps. The flexible convoluted tubing is manufactured from polyamide nylon and is therefore resistant to all fuel types including alcohol blends such as E85 and suitable for EFI fuel pressure.
These are the same machined aluminum injector seats used in Radium fuel rails. They are required when converting an aftermarket injector that uses a 14mm lower O-ring.