100% natural latex is naturally abrasive, and will therefore grip the layers surrounding it. This means it wont slide or bunch, even after twenty or so years of nightly use by mattress owners. Furthermore, a huge advantage to non-glued layers (both immediately when you receive your mattress or years down the road if your comfort needs change) is that if your mattress is too firm or too soft, you can simply exchange a layer of latex to a firmness of your liking vs. returning the whole mattress.