Industrial Milton design coupler plug. This plug design is considered the industrial standard. Can be identified by the 3/16 In. pilot and flat bottom V-shaped ball groove. Conforms to ANSI (NFPA) T3.20.14-1990 dimensions. Conforms to ANSI (NFPA) T3.20.14-1990 dimensions. WARNING: Marring or defacing the protective plating on this product can expose you to Lead a chemical known to the State of California to cause birth defects or other reproductive harm. For more information go to - www.P65Warnings.ca.gov. - Nickel (Metallic)