Audemars Piguet, Royal Oak Jumbo, Ref. 540 ST series B, No. 998xx, B18xx, 158xxx, certificate of authenticity mentioning the sale date of March 18, 1976. An exceptional and extremely rare waterproof steel sports watch, octagonal screwed steel bezel, black tapestry dial with applied logo at 6 o'clock, luminous gold applied hands and hour markers, date at 3 o'clock. Screw-down caseback, mechanical extra-flat self-winding movement caliber 2121, original steel bracelet with folding clasp. Audemars Piguet certificate of authenticity dated July 3, 2018 mentioning that the watch was sold in Italy. Created by the famous designer Gérald Genta. Absolutely exceptional condition for this unobtainable B version, even rarer than the very first A version of the Royal Oak. With its period booklet, case and service box. Diameter 38 mm A exceptional and very rare waterproof stainless steel wristwatch, screw-down bezel, black tapisserie dial with applied AP at 6, gold luminous hands and indexes, date at 3. Screw-back, automatic winding very flat movement caliber 2121, original stainless steel band with deployant buckle. Original Audemars Piguet certificate of authenticity from July 3rd, 2018, stating it was sold in Italy on March 18th, 1976. Excellent condition for this B series, rarer than the A. Original period booklet, box & service box. A legendary design by Gerald Genta.