Here are two things you might not know about Pearl Jam guitarist Mike McCready: he's got a side project called Flight To Mars that plays covers of '70s British rock outfit UFO and, for more than 20 years, he's been battling Crohn's Disease.

At least once a year, McCready brings both those worlds together and shines a spotlight on CCFA with an annual benefit show in Seattle.

Over the weekend, McCready brought along a few famous friends for the 14th annual installment of the Flight to Mars benefit at the Showbox. He enlisted his recent Mad Season collaborators – Guns N' Roses bassist Duff McKagan and Screaming Trees drummer Barrett Martin – for a set that included covers of Motorhead's "Ace of Spades," AC/DC's "Let There Be Rock" and plenty more. Check out fan-recorded footage (via Alternative Nation) above and below.