Mounts in place of the original nut using shims "normally" provided as stated in the manual (I didn't need them) The pickup reproduces a correct sound of the body and strings (vs pickup to stick on the body) however the nut being less rigid I find that my guitar (Alvaro N°30) has a less clear sound acoustically. The supplied cable is not of very good quality. To summarize, if you use your acoustic more often without amplification prefer a pickup to apply on the top cheaper, otherwise opt for an AST/UST installation (BBand or Schertler).