SOS company - Strumenti Ottici Subacquei – Underwater Eye Instruments was founded in Turin in the middle of 1950 from Eng. Victor Aldo De Sanctis and Eng. Carlo Alinari. De Sanctis was a famous person in the underwater video film sector since 1935 when, using a self-made video camera housing, shoot the first Italian underwater video, one of the first in the world to document a water polo training in the swimming pool.
SOS name soon become popular for its oil-bath depth gauges and, above all, for its Decon gauge, designed by Alinari in 1958 and presented in Barcelona during CMAS general board meeting in 1960. It was an extremely innovative analogic instrument, able to show automatically the safety stop times and to count stops and times of the eventual decompression. It anticipated of almost twenty years the electronic diving computers soon becoming a worldwide diving leading device, shown in many catalogues of diving gear companies, customized with their logo. Known from the beginning as DCP, from the name of its first model, its functioning was based on a small sealed housing filled with air in contact with a porous ceramic pad, simulating the nitrogen absorption in the in tissues. During diving, with the increase of depth pressure, the air filtered through this pad towards a Bourdon tube pressure gauge which, acting on some mechanisms, indicated the times in the quadrant.

Seen De Sanctis experience, the company addressed also to the photographic sector, creating housings for video cameras and a series of accessories for the Calypso Phot, after its introduction in 1962. The company did not ignore either the diving spear gun sector, one of the most important sectors in those years, by launching in 1967 the exclusive Ringo Hydromatic spear gun with the hydro-pneumatic operation.
During the following years, the decon pressure gauge developed in a wide range of models, together with other special instruments such as the Split-Stopper in 1978, which emitted an alarm during a too quick ascent and the Table Timer in 1984 to calculate decompression times, dedicated to these people who were reluctant of those electronic innovative instruments just born. The Table Timer has been the last item produced by this company, which disappeared in 1985.

These published pictures come from the Historic Archive of Tarcisio Basso.