Abstract: A cap for sealing a vial is convertible between a child-resistant side and a non-child-resistant side. The cap has an external housing having a top and a side wall. There is at least one channel running around a periphery of the top and a plurality of detents disposed around the interior surface the side wall. There is an insert held within the housing by the detents. The cap is lockable on a vial having external locking lugs, in a child-resistant position by placing the cap on the vial and turning the cap so that the detents engage the locking lugs. The cap can close the vial in a non-child-resistant position by placing the cap on the vial with the top surface of the top facing the vial and pressing the cap onto the vial so that a top edge of the vial inserts into the channel.