This is a NEW OLD STOCK (NOS) British Prefocus (BPF) or P36 base (12V, 45W) TUNGSTEN driving/spotlamp bulb. It is correct for SLR576, SLR700 and Spot Ranger lamps.
These have a vertical filament, which throws a conical beam, correct for a driving lamp, although they fit in foglamps as well.
Our bulbs come from several manufacturers, including LUCAS, Stanley, etc.
Reproduction 185 bulbs have just started to be remanufactured after a hiatus of several years. Large suppliers frequently provide reproduction 323 foglamp bulbs in place of 185 bulbs, which fit but throw a different shaped beam and are not correct. We have a large supply of these correct 185 driving lamp bulbs.