As for all RESSENCE watches the essence of TYPE 5 is its main function - the expression of Time. To achieve the best-ever readability underwater, the complete ROCS 5 - all 142 components, including the dial - is immersed in 37.5 ml of oil. Indeed the use of oil has one ultimate advantage. It cancels out what is known as Total Internal Reflection. Typically, under water, a traditional diver’s watch needs to be viewed straight on in order to be read properly - otherwise refraction turns the glass into a mirror. But not with the oil-filled TYPE 5 . The use of oil ensures complete legibility whatever the angle of view. A first for a mechanical watch.