14x22" on matte thin stock printed before the event promoting a week long residency by Country Joe and The Fish, co-starring The New Age, at The Matrix in San Francisco from Sept. 23rd through 29th, 1966. The Matrix was managed by Jefferson Airplane's Marty Balin and hosted many blues and folk acts showcasing the emerging San Fran sound. Designed by Jon Adams and printed by Berkeley Free Press Offset Printing w/Union Label emblem above fin of whale image at bottom left. Poster was folded and shows obvious visible wear including age toning, foxing, scattered wrinkling/creasing and multiple rips/tears w/paper loss from use clearly seen in images. Good.