This paper provides a descriptive review of a class of stone tools from the interior highlands of Borneo that are formally defined in this paper as ‘cylindrical stone adzes.’ The implements discussed are all housed in the archives of the Sarawak Museum in Kuching, Malaysia. They form part of an ethnographic and archaeological collection that was largely compiled by Tom Harrisson during his tenure as Curator of the Sarawak Museum from 1947 to 1966. These tools have been described and discussed in previous publications and I add detail to these descriptions that includes a technological and functional assessment. The results of this study show that these tools are a type of hafted stone adze used to process the starchy pith of sago palms. These tools were not in use during the historic period and may have been abandoned within the early first millennium AD, associated with a decline in the role of sago as a food staple.