Fender Precision and Jazz basses have bolt-on necks - the neck of the instrument is literally bolted onto the body. Some modern basses feature ‘through-neck’ designs - this sometimes means that the entire instrument is made from a single piece of wood or laminate.
bolt-on neck and through-neck
The neck joint of a bass is a conduit for the vibrations. If the joint is unstable, the bass may have tuning or stability problems. Through-neck basses have a softer tone and greater sustain, whereas basses with bolt-on necks sound a little harder. It’s very important to have good neck stability - some basses have as many as 6 bolts rather than the usual 3 or 4.
