Replacement nuts for your Strat, Tele, Jaguar, Jazzmaster or Mustang. Brass is known for it's pleasing sonic attributes in guitars (as can be seen in the widespread use of brass Telecaster bridge saddles, for instance). These nuts will absorb less of the vibration of the strings than the usual plastic equivalents, allowing your open strings to ring out unimpeded.
These nuts come in one of two sizes - 42mm and 43mm. This is the measurement of the length of the nut. Both lengths share a common width of 4mm and height of 5mm.