Hirschmann 731 72 Series Crimp Contacts for NR Series Connectors 0.5 to 1.5mm – Hirschmann 731 724-221, Crimp socket contacts that accept 0.5 to 1.5mm² cable, suitable for Hirschmann NR-series and ST-series (5-pole) connectors. Hirschmann 731 724-221 RBC 162 Ag Rolled Plated Crimp Socket 0.5 to 1.5 mm2