The Yema YGMT21A39-AM2S is the Superman Worldtime GMT Scales Slim Edition, a 39mm automatic dive watch inspired by Yema’s early 1990s Hattori period.  It features a matte black dial with oversized "maxi" markers, a 2.60mm double-domed sapphire crystal, and the in-house YEMA3000 GMT caliber with a 42-hour power reserve. 

• Case Diameter: 39mm

• Case Thickness: 11.20mm

• Lug-to-Lug: 48mm

• Lug Width: 19mm (tapers to 20mm at clasp in some descriptions, but standard is 19mm)

• Case Material: Brushed 316L Stainless Steel

• Water Resistance: 300m (30 BAR / 990 ft)

• Crystal: 2.60mm double-domed sapphire crystal

• Crown: Screw-down crown with Yema logo

• Bezel: Unidirectional rotating bezel with aluminum insert, 24-hour GMT graduation, and Yema's signature bezel-lock mechanism at 3 o'clock. 

• Type: In-house automatic GMT movement

• Functions: Hours, minutes, seconds, date, GMT (24-hour hand)

• Frequency: 28,800 vibrations per hour (4 Hz)

• Jewels: 29 jewels

• Power Reserve: Approximately 42 hours

• Winding: Self-winding with ball-bearing rotor; manual winding capable

• Hacking: Yes (seconds stop when crown is pulled)

• Origin: Manufactured for Yema (based on a modified Soprod/ETA architecture but branded and adjusted as in-house YEMA3000)