Duracell's guarantee results from significant improvements to their alkaline cells, including the purity of ingredients and upgrades to the battery cell in order to preserve power. The Duralock guarantee gives you the comfort of knowing that the Duracell batteries sitting in your drawer will still work when they are needed most.
This pack includes 4 AA Duracell batteries.
They're batteries, and they work well. They add a little bit of extra usage time in comparison to no name batteries, but I'd really only want to buy these again if they were on sale.