Hagstrom 1968 guitar catalog. Front cover. 12-string guitars were all the rage in the second half of the 1960s. At this point in 1968, Hagstrom offered several multi-stringed instruments - all with the special design 'H expander-stretcher' truss rod, for low action and easy playing. The title of this catalogue is The Fastest Playing Neck in the World. The guitar pictured on the cover was the F-12-S solid-body twelve string. This is the American name for this instrument - elsewhere it was designated H-12.
There are parallels with this cover image, and Hagstrom advertisements produced by Unicord in 1967 - notably the Long and Slippery advertisements featuring Frank Zappa, who holds the F-12-S in a rather similar manner. (Actually the Zappa advertisement seems to be a collage produced from the image shown here).