Maybe it is cast iron? Equivalent to a ground anchor.
Mine is attached to a (thick) wooden stair post. If someone saws through to nick my bike it is ample enough to justify the insurance company paying out - noise would be heard in the whole building, time taken to saw through...
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Mine is attached to a (thick) wooden stair post. If someone saws through to nick my bike it is ample enough to justify the insurance company paying out - noise would be heard in the whole building, time taken to saw through...