Isanrẹn can be used to lock up rooms such as the aza emwin arhe. This is a vault or a storage room for valuables, for example money, ivory, artifacts, coral beads and clothes. Isanrẹn were cast in brass, which indicates that they were used within palaces. Others were made in a combination of iron and brass and would have been produced by both the Igun-Eronmwon and the Igun-Ematon. Some pieces may include coral or agate inlays, suggesting they would have been particularly important and possibly used only in Ọba Palace.