Material A) Ductile Iron B) Grey Iron 1) Product information: Manhole covers are manufactured for road construction, ... defects. 2) Material A) Ductile Iron GGG500-7, GGG 400-12, GGG600-3, GGG700-2 B) Grey Iron GG20, 25, 30, 35 3 ... ) Packing Steel or wood pallet, or as per customers' requirements. cast iron grating