I purchased this product because the little 'feet' of my netbook have worn out, causing it to tip over constantly. The heat reduction balls fixed this problem instantly (the heat reduction is a nice extra feature, haha). They were much bigger than I expected, but that actually turned out to be a good thing. Using my laptop is far more comfortable now.
A small con however is that the glue didn't stick very well and the balls started falling off after a couple of days. A drop of superglue fixed this problem quite easily though.
And an extra perk: I was quite happy to have received the black version instead of the pink!