This package of Lineco Buffered Interleaving Tissue Paper includes 100 sheets of 25cm by 38cm paper that have a 3% calcium carbonate buffer added to it during the paper making process. This buffering agent raises the pH level of the paper to approximately 8.5, making it non-acidic. The reservoir of calcium carbonate also helps neutralise other acids in the environment that would normally make paper become acidic over time. Ideal for storing collectibles, especially paper items.