This close-up shows the locking tab that keeps the batteries in place. The batteries are stored loosely in the caddy, while the tab keeps them from slipping out. The tab is beveled so only a slight pressure will force the tab back and allow the battery to be pushed free. The same bevel is on the opposite side of the tab, which allows the cells to be easily inserted into the caddy. Simple, but effective.
Storacell caddy locking tab