Seiko Prospex Sky watches

Seiko Prospex Sky is the pilot's side of Prospex, Seiko's sports watch line. Seiko took Prospex to the skies in 2016 with the Radio Sync Solar World Time Chronograph, and the family now spans solar chronographs and a mechanical watch with a rotating bezel.

That first watch is the SSG001. Its calibre 8B92 is solar powered and sets itself up to three times a day from the time signals of Japan, China, the United States and Germany. It shows 25 time zones, times events to 60 minutes in fifth-of-a-second steps and carries a rotary slide rule on the bezel for converting distance, fuel, weight and speed. The pushers at 3 and 9 o'clock have differently shaped tops to reduce the risk of pressing the wrong one. The steel case is 47.8 mm across and 14.5 mm thick, under a Hardlex crystal with an anti-reflective coating, and LumiBrite coats the hands and markers. The SSG003 is the same watch with a black hard coating on case and bracelet, and the SSG005 comes on calf leather. The SSG011 and SSG013 put the 8B92 in a smaller case, 45 mm wide and 12.9 mm thick.

The SSC607, SSC609 and SSC611 are solar chronographs on calibre V192, in a 45 mm case 11.6 mm thick under sapphire, with a rotary slide scale on the bezel. Besides the 60-minute chronograph, the dial has small seconds, a 24-hour hand, a date and a power-reserve indicator.

The SRPB57 is the mechanical one: a 44.7 mm steel watch, 13.3 mm thick, with a rotating bezel and the 4R35, an automatic movement that can also be wound by hand, with hacking seconds and a date, visible through a screw-down exhibition back. The SRPB59 pairs the same case with a cream dial, and the SRPB61 is another black-dial version.