REAR FOG LAMP BULB

[Anonymous]

I have a J-Spec 2 and so i have a rear fog in the lower grill and 2 rear driving lamps on the back (2 either side).  1 set gets brighter when you brake, the other stays normal.  I'm thinking of changing one set into fog lamps (so they will no longer be on when driving)!  I have seen how I can do the wiring which just looks to be a case of connecting the current fog lamp wire to the existing rear driving lamp and then running a loom over to the other side.

However,  the fog lamp bulbs I have seen for the 2 (in places like halfords) are a lot bigger than the normal bulb.  What is the size of it in a standard uk 2?  Is it small like the others but a higher wattage or does the cluster have room for the big bulbs?  I might have to change the whole cluster if i can't get a small bulb!