The last word Guidebook to GBL: Added benefits, Employs, and Safety Strategies ???? ???? Precisely what is GBL? GBL (Gamma-Butyrolactone) is often a chemical compound commonly used in industrial and pharmaceutical purposes. It is a precursor to GHB (Gamma-Hydroxybutyrate), a material recognized for its sedative and euphoric results. GBL is commonl