The 5167A is the steel Aquanaut with date, introduced in 2007. The Aquanaut arrived in 1997 as a younger, sportier counterpart to the Nautilus.
It shares the rounded octagonal shape of the bezel but has a face of its own: a dial with an embossed chequered motif and a strap in composite material bearing the same pattern, which withstands water and perspiration. The case measures 40.8 mm, taken from ten to four o'clock.
Inside is a self-winding movement with date and a gold central rotor, visible through the sapphire caseback: calibre 324 S C, and from 2019 the 26-330 S C. The watch is water-resistant to 120 metres.
The composite strap is a wearing part. On a pre-owned 5167A we therefore look at the condition of the strap and the folding clasp, and state whether an original spare strap is included.
We also assess the case for polishing marks, the dial and the movement, and compare the numbers with the certificate.
Those who prefer a chronograph will find the 5968A within the Aquanaut line; our full selection is on our Patek Philippe page.