Rancilio Silvia 1/8" F x 1/8" M Stainless Supply Hose
This was initially designed for post 2008 models, commonly referred to as "Version 3". Now, all models must us it in the event the small fixing nuts that compress the PTFE hose of the older version are damaged, or in the event the PTFE tube itself becomes unusable.
This new hose works and connects directly in conjunction with the expansion (Over Pressure, or "OPV") valve. They now connect to the pump with an elbow fitting that comes off of the pump, instead of the old compression type fitting, and thread directly into the expansion valve.
To install, remove the fitting (if yours has it) from the expansion valve water inlet. Wrap the male threads of the hose with white plumbers tape. PTFE tape is recommended for all of the fittings that seal cold water. Thread the male portion of the hose into the valve. Remove the old compression type fitting (if yours has it) from the water exit portion of the vibratory pump. Thread the new fitting into the pump. Last, thread the female portion of the hose onto the new fitting coming off of the pump.
The material superiority is obvious. Same as the brake lines on a motorcycle. Now we'll just have to see if the clown (me) w/ the screwdriver and a wrench (12mm crowfoot) got it assembled properly w/ the plumber's tape.