Neoprene Laptop Bag.

Step 3 Choose your neoprene.

Neoprene is a closed-cell foam. Closed cell foams are basically thousands of tiny bubbles surrounded by rubber where none of the bubbles join any others. This confers their water-proofness. Open cell foams are those where all the bubbles intersect and overlap. These become waterlogged and don?t trap air which is a better insulator than any plastic or rubber by itself.