The Steel Bore Head is a component from the Railcraft mod. This component is used to operate the Tunnel Bore properly. It is the piece that allows the Bore to break blocks, like the Iron Bore Head and the Diamond Bore Head. This Bore Head has a durability of 3000, and does not allow the Tunnel Bore to mine Obsidian. This Head mines blocks 20% faster than the Iron Bore Head.
It goes in the Head slot of the Tunnel Bore's GUI. It will begin mining as soon as it has a head, tracks, fuel, and ballast.