The personal air filter is becoming an essential item for both regular and casual pot smokers. For medicinal patients, especially, it may be crucial. Whether at work, on the road, or at home with family, treating health conditions with weed incognito, to avoid any lingering stigma around cannabis use, is key for effective administration.

Eco Four Twenty is a new business out of Toronto, which sells personal air filters from a website hosted by the online e-commerce web host Shopify. It's not the plug-in kind of filter that produces UV light and kills bacteria in the air—instead, it lives in your bag or pocketbook, which you exhale into after taking a hit from your vaporizer.

Consider it the Stark Industries version of the dryer sheet-stuffed toilet paper roll. It has the same dimensions, except the cardboard is replaced with aircraft-grade aluminum.

Canadian entrepreneur Michael Ghazal, 29, started Eco Four Twenty after selling his half of his first major business venture, the Survivor Filter, to his cousin. That product, a portable water filter, was created to improve on a competing product, the Life Straw, and reduce the amount of plastic waste that resulted from its use.

In the same vein, Ghazal sees Eco Four Twenty as a sustainable alternative to other filters, such as Southern California's Smokebuddy, which can be found in Portland dispensaries and head shops. Whereas the colorful, plastic Smokebuddy is eventually thrown away after the filter expires, the Eco Four Twenty's canister can be unscrewed and replaced at the end of the filter's life.

The device retails for $30 and comes with a lifetime warranty that promises a replacement or full refund. Filters are sold two at a time for $15, including shipping. The mouthpiece is made of silver-infused silicone, and the entire thing is simple to unscrew, take apart, clean and put back together.

There is, however, a fairly large drawback, one that is a particular issue in Portland: Should you have a beard, pressing your mouth into the top to exhale will result in a failed seal. Vapor will expel from either end that isn't held fast and tight. So unless you put your mouth fully around the gaping hole and exhale, the thing won't work as advertised—and in that case, proper use will leave you looking and feeling pretty dumb.

By next Christmas, the company plans to offer an inverted mouthpiece attachment that should solve the problem. It'll look a bit phallic, Ghazal admits, but that's a small price to pay for sustainable smoking.

BUY IT: Order the Eco Four Twenty Personal Air Filter at ecofourtwenty.com.