Recreational marijuana is legal in Colorado. But that doesn't mean residents want the air to smell like a student's living room on the day GTA5 got released. Denver is getting more calls to enforce an 'odour ordinance' that can impose a fine on violators. To find them, the city relies on a device called the Nasal Ranger.

The Nasal Ranger is a cone-shaped thing resembling a megaphone that's made by St. Croix Sensory, a company based in Minnesota. It samples the air to help an operator detect the presence and strength of odors. As others have noted, the device looks exactly like a scaled-down and streamlined version of the Smell-O-Scope created by Professor Farnsworth on the mighty Futurama.

A Google image search of the Nasal Ranger is extremely rewarding: