The reference was produced in yellow gold, pink gold, white gold and platinum across a total of four series with production spanning over 19 years. It is estimated that throughout its course of production, over 4,000 examples of the reference were produced. The 2nd series produced between 1987–1990, showing some overlap with the first series. It features a solid screw back caseback “E – Etanche”, feuille hands and baton indexes. Produced in all four case materials with an estimated 650 examples produced across all metals, with 150-200 of those being reference ref. 3971.

The present second-series example in yellow gold features a sapphire screw-down case back, designating it as ref. 3970E, with “E” standing for étanche, the French term for waterproof. Notably, it bears prominent and crisp “big hallmarks”, including the “750” gold purity mark and Atelier Réunis casemaker’s key number 28, stamped clearly on the outside of the lug. The “big hallmarks” is particularly significant, as it only began appearing midway through the second series production. The condition of the present timepiece is very well-preserved, displaying a thin layer of attractive patina on the caseband and bezel.