The problem with the Costco ones is the drawers have a friction system to keep them closed. If your shed isn't heated you will have a hell of a time opening the drawers in the cold. Also the drawers don't come out all the way like on a snapon, as the last inch or so of the drawer is still in the cabinet when fully open. This being said, I would buy the costco boxes again, as the fit and finish seem good, but I would gladly spend a little more and have better slides, and positive locks on the handles.
On all equipment there are 2 levers...
Lever "A", and Lever F'in "B"