Vintage hydrant flow gauge.

Fullsize image: https://diqn32j8nouaz.cloudfront.net...e_fullsize.jpg



Previously:

Fire hydrant cutaway - photo
Firefighter gets blown away by fire hydrant - GIF
Firefighting foam aerator - GIF
Fire hose winding attachment for cordless drill - GIF, video, photos
Firefighting missiles for highrise buildings - GIF