Armin Strom Gravity Air TI13-GA.50

The micro-rotor sits on the dial side, so you watch the AMR13 calibre wind itself: only the top half of the rotor shows as it turns, beside the small seconds, with the hands set off-centre on a chapter ring shifted to the left. Armin Strom rates the in-house AMR13 at five days of power reserve, and the bridges are hand-engraved with a theme for each element. The case is 43.4 mm across and 13 mm thick, under sapphire.

The element sets the metal. The Gravity Water (ST13-GW.50) has the same case in stainless steel, the Earth (ST13-GE.90) in black PVD-coated steel and the Fire (RG13-GF.90) in 18k rose gold. The Gravity Date Air (TI14-DA.50) keeps the titanium case and swaps in the ADD14 calibre, which adds a date with a 24-hour day/night display. The Tourbillon Gravity Air (TI14-TA.M.50) swaps in the ATM13 tourbillon calibre in a run of 50.