...These are the correct factory "ATE" sodium-filled valves used by Porsche on the 911 RSR racing engines. Sodium-Filled for a little better cooling. The first two-photos shows Ike (Ollie's) using his pneumatic "valve-keeper removing tool" https://pbase.com/slidevalve911rsr/image/54979881 which makes the job of R/R the valves go a whole lot quicker!
Specs: Intake Valve Size: 49mm - Exhaust Valve Size: 41.5mm - Intake Port Size: 43mm - Exhaust Port Size: 43mm