Harwin also manufactures a variety of female threaded spacers. Brass metric spacers come with M2.5, M3, and M4 threading and a 4-40 UNC threaded spacer is also available.  For a non-conductive spacer, Harwin provides an M3 threaded plastic spacer beginning at 6mm up to 25mm.  4-40 UNC threaded spacers are provided in sizes ranging from 6mm up to 50 mm.