Manufactured from 1215 steel. Kit include quantity 5 of an assortment of 18 & 12 mm bungs, plugs anti-seize compound and copper washers. Includes: 18mm bungs - 3/8". 18mm bungs - 1/2" with step. 18mm bungs - 1" angled. 18mm bungs - 1" straight. 18mm plugs - 1" Hex head. 18mm plugs - 5/16" Allen head. 18mm copper crush washers (Qty. 10). 12mm bungs - 5/16" with step. 12mm bungs - 1/2". 12mm plugs - 5/8" Hex head. 12mm plugs - 6mm Allen head. Anti-Seize compound packets (Qty. 10).