Ferrous HMS 1 ISRI / REMA Specification 200 No. 1 heavy melting steel.Wrought iron and/or steel scrap 1/4 inch and over in thickness. Individual pieces not over 60 x 24 inches (charging box size) prepared in a manner to insure compact charging.201 No. 1 heavy melting steel 3 feet x 18 inches.Wrought iron and/or steel scrap 1/4 inch and over in thickness. Individual pieces not over 36 x 18 inches (charging box size) prepared in a manner to insure compact charging.202 No. 1 heavy melting steel 5 feet x 18 inches.Wrought iron and/or steel scrap 1/4 inch and over in thickness. Individual pieces not over 60 x 18 inches (charging box size) prepared in a manner to insure compact charging.