"A Spacer is a threaded separator of defined length used to raise one assembly above another. They are usually round or hex (for wrench tightening),often made of brass come in female-female forms.
In electronics they are frequently used to raise a printed-circuit board above a surface. Insulating standoffs keep two parts from touching each other, thereby preventing electrical shorts. When used to fasten cable connectors (i.e.D connectors) together,they are called jack screws."