Grease Subtractor (GS) can be used as an additive to boost your prespray with extra grease cutting performance. Avoid having to re-apply prespray to that trashed-out carpet by adding GS, saving you both time and money. GS is derived from natural citrus oils blended with the industries most safe, complete and powerful blend of grease cutting agents. This is a must have item for every professional carpet cleaner. Avoid use on polypropylene (Olefin).