Porsche 911, 924S, 928, 944, and 968 Bosch "Platinum Plus 4" Spark Plug.
Bosch® - OE Specialty Platinum Spark Plug
Bosch Platinum Spark Plug 6726
Platinum+4 Spark Plugs - Platinum+4 Spark Plugs - Bosch Auto Parts
BOSCH Platinum Plus Spark Plugs 4417. Platinum Spark Plug Equivalent to FR6DCPLUS, FR6DDC, FR6DTC, and FR6KDEO OR NGK BKR7EKC for BMW R1100, R1150 & R1200.
Bosch Platinum Plus spark plug review - MKRD.info
Bosch® - Super Plus™ Spark Plug
Bosch Platinum Plus Spark Plugs #4007 Pack of 4 NOS | Factory OEM Parts