end of a string 7 at the opposite end with respect to the pegbox 4 the strings 7 are moreover connected to the engagement points 15 of a tailpiece 8 fixed to the sound box 2 with the bottom or tail portion 14 in such a way said that by turning the pegs 5 the tension of the strings is adjusted and consequently it is possible to tune the instrument with reference to fig5 a peg 5 according to the invention is described comprising a generally frustoconical stem 9 with axis 12 which at the end of larger diameter terminates with a manual gripping portion 10 the peg 5 is made up of two parts each made of a different material and in particular a central core 11 surrounded by a peripheral portion 13 the central portion 11 is made of a non metal material preferably selected from among carbon fibre kevlar and composite materials in general whilst the outer portion 13 is made of wood also to enable easy machining thereof to reduce the diameter if need be in a preferred embodiment the peg 5 is obtained by making the central bore corresponding to the portion 11 and then inserting the central portion 13 after applying a glue suitable for the materials chosen advantageously since the portion 13 is not made of metal material it can be bored in a transverse direction to create the bore 20 for attachment of the string to the peg without deviating the drill and damaging the peg as would occur if a metal insert were used with reference to fig7 and 8 a tailpiece 8 according to the invention is described made up of two layers 16 17 stably coupled by.