Lots of watches adopt a diver aesthetic. Yet it takes robust water resistance to elevate a timepiece from an accessory to a professional tool. Unimatic's U1S line does so using several intelligent design choices. Both the U1S-PD3 and U1S-PD5 have 40mm 316 stainless steel cases, mono-directional rotating bezels with lumed ceramic inserts, and Superluminova-filled hands and indices set on matte black dials. Swiss-made Sellita automatic movements power both, protected by a double rubber O-ring mechanism on the screw-down crown. But while the PD3 is rated for 300 meters of water resistance, the PD5 uses a thicker crystal and thicker conversion scale screw-down case back to boost structural integrity, upping its rating to an impressive 500 meters. Both watches come mounted on a two-piece TPU strap and arrive with an extra grey seatbelt NATO strap and warranty card with a unique ID seal inside a Unimatic tough carrying case. Limited to 500 examples of each.