I bought the PG27-USB mic which comes with a stand adapter. But the "adapter" doesn't fit a standard Desk stand. Please clarify.
Shure microphones and Shure mic holders have a standard 5/8"-27 internal thread. This is the U.S. standard for mic stands.
Most Shure mics are also provided with an metal insert/adapter for European stands that have a 3/8" thread - typically this Euro adapter is brass or silver in color. If the Euro adapter has been threaded into the 5/8" mic stand thread, the Euro adapter can be removed; it simply unscrews.
More information: Euro Adapter