Sodium dithiophosphate is the salt with the formula NaPSO.  It is usually supplied as the hydrated solid or as an aqueous solution together with other thiophosphates such as sodium monothiophosphate and sodium trithiophosphate.  It is a colorless compound, but commercial samples can appear dark owing to the presence of impurities.  It is used to facilitate the isolation of molybdenum from its ores.