3M Scotchlok Insulation Displacement Connector 557 provides a dual element connection. The connector is polypropylene insulated and used to connect 2 wires while insulating the connection. It is self stripping and flame retardant.3M Scotchlok Insulation Displacement Connector 557 is 600V rated for building wire and 1000V rated for signs, fixtures and luminaires. It withstands temperatures of 221 degrees F (105 degrees C). UL Listed, CSA Certified and RoHS 2011/65/EU Compliant.