SAP is an acronym for Super Absorbent Polymer, also referred as hydrogel, sodium polyacrylate, polyacrylate absorbents, or Absorbent Gel Material (AGM). SAP is a petroleum-based product whose job is to absorb and trap moisture, up to 300 times its dry weight, in fact. Dehydrated, it looks like tiny crystals or fine white sand (below left) found inside the layers of all disposable diapers' absorbent core or inside other disposable absorbent products such as nursing pads and panty liners. When hydrated, SAP appears as clear gelatinous blobs as illustrated below. At this point, SAP is present in ALL disposable diapers, green as well as traditional. While plant-based SAP is being produced and tested in labs, as far as we can tell, every disposable diaper in our reviews uses the more time-tested petroleum-based SAP.