Certina "Biostar Electronic

Certina "Biostar Electronic", Grenchen,No. 8644505, Ref. 7506.001. Produced in the 1970's.Unusual center-seconds, water-resistant, stainless steel and yellow gold-plated electronic gentleman's wristwatch with date and indication of the body's "bio-rhythms". two-body, bicolor, polished and brushed, steel screwed-down case back, gold-plated bezel, band and lugs. champagne with applied yellow gold and black indexes, aperture for the date near the 3, below the twelve sector aperture for the polychrome data:- Red : body rhythm for 23 days- Blue: psychic rhythm for 28 days- Green: intellectual rhythm for 33 days."Bâton" tritium-coated and black gold hands.