The black WindTech M-5 is a 5/8"-27 female stand nut used to tightly lock your microphone's orientation on the stand, keeping it in place at whatever angle you might need it at.
The M-5 replaces the small knurled nut that tightens up against your mic clip on most mic stands and replaces it with a large, heavy-duty nut that's faster and easier to tighten.
This package contains five black M-5 stand nuts.