Before buying it, I compared the dimensions my Asus Q-Series 15.6" laptop to the Protek 15" dimensions and thought it would fit. It didn't come close to fitting, which is disappointing because this might be the best quality sleeve I've seen; I loved it. (I suppose that the product dimensions are external rather than internal.)
I think it's semi-rigid design and thick corners would actually protect a laptop better than most of the competition. I would have bought a 17" model if one was offered.
This is an awesome product, but if you have a thick laptop, it probably won't fit. I did notice after the sale that the sleeve is described as 15.6" but the box said only 15". It's questionable if any 15.6" device would fit.