Bolt-in construction is similar to Bolt-on with the exception that the neck fits tightly into a pocket at the neck joint of the body. The Bolt-in method of construction enables the adjustment and even swapping of necks, as does the Bolt-on method. On a true Bolt-in guitar, the neck fits tightly into a pocket, not completely unlike a set neck guitar, but no glue is used. Wood screws or bolts and inserts are used to secure the neck to the body.
The tone of a Bolt-in construction guitar will generally be thinner, brighter, or more articulated than on a Set-neck or Neck-through-body construction guitar. Sustain tends to suffer on Bolt-in guitars as well. There are of course exceptions. Exceptionally well built Bolt-in guitars can produce fantastic sustain and clarity, but the thick crunchy midrange of a set neck guitar is difficult if not impossible to reproduce in a Bolt-in guitar.