The Omega Speedmaster Professional 311.30.42.30.01.001 is the standard-production stainless steel Moonwatch reference that anchored the third-generation pre-2021 Speedmaster Professional lineage, carrying the Hesalite crystal and the manual-wind Caliber 1861 that powered the Moonwatch from 1996 through the 2021 Caliber 3861 transition. The Speedmaster Professional Moonwatch lineage itself traces to 1965, when NASA flight-qualified the Speedmaster for all manned space missions following the 1962 acquisition of the model by Wally Schirra for his personal use aboard Mercury-Atlas 8. The 42mm stainless steel asymmetric case carries the polished sloping bezel with the engraved tachymeter scale, the twisted lugs, and the screw-down crown that have remained unchanged across more than five decades of Moonwatch production. The matte black step dial features applied luminous indices, broad luminous baton hands, and the three classic Moonwatch sub-counters arranged with the 30-minute counter at 3, 12-hour counter at 6, and running seconds at 9. Powered by the Omega Caliber 1861 manual-wind chronograph movement, derived from the Lemania 1873 base, beating at 21,600 vibrations per hour with a 45-hour power reserve. Sapphire crystal caseback, water resistance to 50 meters. Pre-owned.