The Milwaukee AIR-TIP 2-1/2" Magnetic Utility Nozzle (49-90-2033) has integrated magnets that catch metal hardware, preventing damage to bags and filters inside of a wet/dry vacuum. The magnetic strips are located on the front and back of the vacuum tool to catch metal hardware before it gets inside the vacuum. The 2-1/2" diameter allows more debris to flow into the vacuum than smaller diameter tools. The black zinc coating on the magnets prevents rust long-term.