The invention relates to a device (D2) employed in a system for facilitating the assembly of a product, said assembly being carried out by following one or more assembly sequences, an assembly sequence comprising several successive assembly steps graded by execution ranks, said device comprising: a presence sensor (C2), at least one signalling member (V2), a sequencer (SQ2) connected to the presence sensor (C2) and to the signalling member (V2), said sequencer comprising a microcontroller designed to manage said assembly sequence. The invention also relates to a system for facilitating the assembly of a product comprising several devices (D2) connected together via a communication line.