Connector produces strong permanent connections for traditional splices. Pressure-type used in branch circuit and fixture wiring. Recommended for use in applications where substantial vibration occurs. Copper-to-copper applications. WARNING: This product can expose you to chemicals including DEHP which is known to the state of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov - Nickel (Metallic)