A blank can include a main panel and a locking tab extending from and separable from the main panel and including a first tab subpanel, a second tab subpanel, and a third tab subpanel; the first tab subpanel extending from the main panel, the second tab subpanel extending from the first tab subpanel and joined to the first tab subpanel at a first bend line, and the third tab subpanel extending from the second tab subpanel and joined to the second tab subpanel at a second bend line.