Hot Water Pipe Hanging Marker Tag

I am making and selling these, I plan on adding more tags for other utilities like natural gas. I'd like to hear from you guys what would be useful.

The idea here is for basements and crawlspaces, these work better than other options as they are visible below the joists, and could be made from florescent filament for even better visibility. These can be used in construction, or for existing houses for future homeowners or repairmen to quickly find what they need.