what the sharp sign in macro mean?

[ggodw000]

I came accross following defs, what are the meaning of these two sharp sign toward the end of define macro statement?

where:
SW_DEFINE_HANDLE - macro name
object - parameters passed to macro
object##_T - ##???

#define SW_DEFINE_HANDLE(object) typedef struct object##_T* object;

Now I see usages like:

SW_DEFINE_HANDLE(Instance)
SW_DEFINE_HANDLE(lDevice)
SW_DEFINE_HANDLE(Queue)

Thanks.,

[Octocontrabass]

That's the token concatenation operator.