Original 1st printing 13&1/4 x 22&1/2" concert poster for the Only Alternative (and His Other Possibilities) appearing at the Matrix in San Francisco, CA, from 10/18-30/1966.
Artist unknown, not credited, medium-thick flat index stock poster is in very good (B/B+) condition; there is a bit of creasing (a few small hard diagonal bends) in the top/bottom left corners, a series of thin handling/pinch bends along the top/bottom margin, a couple of tiny pin-prick spots along the upper left margin, a stray tiny surface scuff or two and a tiny bit of pencil scratch on the reverse, otherwise fine.
VERY obscure late-'66 Matrix poster with a decidedly non-psychedelic design. Check out this INCREDIBLE footage of a pair of band members being interviewed in the Matrix right around the time of these shows;
https://diva.sfsu.edu/collections/sfbatv/bundles/210748