Alcohol sales have been permitted at concerts for years. But this weekend brings what’s believed to be a first for another type of controlled substance – for the first time, cannabis can be legally sold and consumed at a show.

The emphasis, of course, is on the word legally, as anyone who ever attended a Grateful Dead show can tell you.

San Francisco’s Outside Lands Music and Arts Festival has announced they will offer onsite sales and consumption of cannabis products at this weekend’s festival in a separate, 21+ area that will feature two dozen cannabis vendors.

While California law does not permit cannabis smoking where cigarettes are banned, the San Francisco Dept. of Public Health has issued a temporary waiver on that no-smoking ban, at least for cannabis (regular tobacco is still banned).

The San Francisco Chronicle reports festival-goers will be permitted to purchase up to “7 grams of non-concentrated cannabis, like dry plant material, and 2 grams of cannabis concentrates, which are found in vape pens and edibles.”