Seventy years after they were first described, the function of Traful Instruments is still uncertain. From their morphological design and the associated environmental and archaeological contexts, we postulate that they are part of a specialized 'composite instrument' for fishing. While their characteristics are unique in the context of the lakes and rivers of North-west Argentinean Patagonia, similarities were found with the line-weights which are widely distributed in Magellanic marine contexts.