Locatelli's Op 4 in fact consists of two quite distinct sets of pieces, six Introduttioni Teatrali and six Concerti. It is not clear whether the title of the 'theatrical introductions' should be taken literally, but certainly the works are composed in a striking manner such as would be expected for an overture fighting to catch the attention of a restless audience.

The second half of the set consists of six concertos whose rhapsodic character contrasts with the carefully structured style of the Introduttioni. These works have differing numbers of movements and Locatelli exploits this greater freedom to include a wide range of virtuosic motifs and textural experiments.