The Speedmaster 'First Omega in Space' is a numbered, though not limited, edition of the Speedmaster. It is powered by the hand-wound caliber 1861 movement. Its design is inspired by the watch worn by astronaut Wally Shirra in 1962 as he orbited the earth during the "Sigma 7" mission. As such, it features a case without the (now-) signature sweeping lugs and protected pushers & crown. It is fitted with a sapphire crystal and a CLOSED case-back. It features a 19mm leather strap with pin buckle. Reference: 31132403001001 The bracelets that fit this reference are; 020ST1125560 020ST1565976