A contact sleeve for connecting at least one stranded wire has a receiving region extending longitudinally to a central line. The central line runs parallel to the stranded wire for inserting stripped ends of the at least one stranded wire and has two crimp wings that are each directed towards each other. In the folded state, the two crimp wings clamp the stripped ends. The crimp wings have grooves that run on both crimp wings relative to the central line in the shape of an arrow. The grooves run outwards, in each case starting from the central line and being curved with a continuously decreasing gradient.