True GMT movement with independently adjustable 24-hour hand. Based on Cal. 3135 with GMT complication. Used in GMT-Master II 16710 and Explorer II 16570 (1988-2005). Predecessor to Cal. 3186 which added Parachrom hairspring. Features ratchet-based date advance (vs click spring in 3186).
Movement Type
Automatic
Jewel Count
31 jewels
Power Reserve
50h
Frequency
28,800 vph (8 Hz)
Diameter
28.5mm
Height
6.45mm
Rotor Type
central_rotor
Winding
automatic_bidirectional
Shock Protection
kif
