Released in 1972 and designed by Gerald Genta, watchmaking's most famous designer, the Audemars Piguet Royal Oak was the first stainless steel luxury sports watch ever to exist. Released as a tactic to survive the quartz crisis, the Royal Oak can single-handedly be thanked for AP's existence today due to its astounding success, albeit it wasn't an overnight hit. Its sizeable tonneau-shaped case, signature integrated bracelet, octagonal bezel, exposed screws, and steel construction failed to win over collectors until a few years later. Today, the Royal Oak is one of the most highly-coveted timepieces in all horology as its previously dismissed design details have permeated across the industry and into watches like the Patek Philippe Nautilus, Vacheron Constantin Overseas, Rolex Oysterquartz, amongst many other legendary timepieces.

The overall condition of the watch is excellent. Bezel and case feature sharp bevels and lack any obvious signs of wear or damage. Case features some very minor needle-like abrasions that can also be found along the bracelet, as is commensurate with age and careful wear. Bracelet features 23 links, 9 of which are removable.

Made of stainless steel, the ref. 56175ST aided in popularizing the Royal Oak as it got collectors used to a luxury stainless steel timepiece from a brand like AP thanks to its smaller proportions and less expensive quartz movement.