Day-Date 6610

Second-generation Day-Date with the smooth bezelBezelThe frame surrounding the crystal at the front of a watch., launched with the 6611 in 1957 around an improved 1055 with a free-sprung balanceFree-sprung balanceA balance regulated by changing its inertia with adjustable weights or screws, while the balance spring’s active length remains fixed. It dispenses with the conventional index regulator that changes the spring’s working length. The term describes the regulating arrangement, not a particular hairspring material or certification. and MicrostellaMicrostellaRolex’s system of small adjustable screws or nuts on the balance wheel, used to change its inertia and regulate the watch’s rate. Introduced as screws in 1957 and developed into nuts in 1983, it allows rate adjustment with the movement still cased. The name identifies the Rolex system, rather than every adjustable-inertia balance. regulation. Replaced by the 1800 series in 1959.