Bass equivalent of the Apollo V266 electric six-string. The Apollo IV was an Italian-built Vox bass, single cutaway, with built in electronic effects. A similar model, without effects, the Saturn IV was also available. Manufactured at the E.M.E factory, from 1967, primarily for the American market.
The following description is reproduced from the 1967 Vox: it's what's happening brochure
An exciting all new 4-string Florentine cutaway electric acoustic bass guitar. Has built-in G tuner, distortion booster, treble and bass booster. All new easy-to-fret fast-neck features VOX T-bar and adjustable steel rod. Exclusive Ferro-Sonic bass pickup. Fully adjustable bridge. One volume, and one tone control. Chrome plated machine heads. Sunburst or Cherry.