Editorial
The Type 5 takes Ressence's oil-filled display concept and waterproofs it to 300 meters, which sounds straightforward until you consider what that actually requires. The ROCS 5 module is pressurized with oil, and getting that system to survive depth meant engineering a pressure-compensation valve that equalizes internal and external pressure as you descend. No other watch on the market works quite like it.
Ressence launched the Type 5 in 2015 as a direct response to enthusiasts asking whether the oil-filled Type 3 could be taken diving. The answer was yes, but it required a complete rethink of the case architecture. Benoit Mintiens, the Belgian designer behind the brand, had to solve the problem of a sealed, oil-filled module inside a case that also needed to flex with external water pressure.
The solution is a flexible membrane and compensation valve that keeps the internal oil pressure matched to ambient pressure at depth. It remains the most technically demanding reference Ressence has made.
The oil in the ROCS 5 module is the whole watch, and it ages. Yellowing over years is well-documented on older examples; inspect the dial carefully and ask for photos in natural light before buying secondhand. The compensation valve is a proprietary Ressence system and cannot be serviced by anyone outside the brand's authorized network.
Battery replacement (the e-Crown variant) and any oil-related service must go back to Ressence directly, which means long turnarounds and costs that surprise buyers used to mainstream service pricing. The 46mm case is genuinely large; wrist time before buying is strongly recommended.
