Sodium Hydrosulfite (or Hydro) is a universal reducing agent that is used for indigo dyeing. It is also used as a non-aggressive alternative to bleach for removing color from dyed fabrics and for whitening antique textiles. WARNING: HARMFUL IF SWALLOWED. Give water of milk if swallowed and call a physician. Avoid contact with eyes. Keep out of reach of children. Do not expose to excessive heat. This package contains Sodium Hydrosulfite, One Pound. Made in the USA.