This nut is made of nickel silver and has a straight knurl.  the thread is 1/2 x 32 and it is a component of the large detachable brace post assembly   

Nickel Silver 5/16 x 32 Knurled Nut is part of the small detachable brace post assembly

New, more ornate Large Detachable Brace Post No Radius includes:1/2 x 32 Knurled elegantly nickel silver nutBrass Plug Nickel Silver Threaded Post without the RadiusOAL 1.055"   Give your...

Nickel Silver Nut Stop is part of the small detachable brace post assembly

Large Detachable Brace Post No Radius includes: 1/2 x 32 Knurled Nickel silver Nut Brass Plug  Nickel Silver Threaded Post without the Radius OAL 1.055"