I'm not certain, but I believe that is a Tequipment piece through Porsche. I just bought a low mileage slightly used 911 C4S Cab which has that shifter. It looks great.
It gets very cold too in winter but this is really not a problem...remember the aluminium gets lovely little scratches with wedding rings etc etc (NB if RHD, as in the UK, the left hand operates the gear lever and it also has wedding rings etc)...