The Alpina Heritage Automatic is a so called field watch that takes you back to the earlier years of the last century. It comes in two variants
Alpina caliber AL-520 (base Sellita caliber SW200-1 b | Automatic | Diameter: 25.6 mm (11½ lignes) | Thickness: 4.6 mm | Frequency: 28’800 vph (4 Hz) | Jewels: 26 | Stop-second device | Hours, minutes, seconds | Power reserve: 38 hours
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Alpina uses the name AL-520 also for skeletonized versions. Which are possibly the SW200-1 S a or b or c depending on the finish. The Alpina caliber AL-525 is the same however with a date (Sellita caliber SW200-1 a).
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Watches with the Alpina caliber AL-520
A cool new Extreme model, the Alpina Alpiner Extreme Skeleton Automatic, with an open-worked dial. Or better, there is no dial
Lovers of classic divers who want a less vulnerable and new watch, this Alpina Seastrong Diver 300 Heritage might be a good option