Anti-Chlor Concentrate, sold per 8 ounce (227 gram) package. A sodium bisulfite compound used to neutralize residual chlorine when removing color with hypochlorite bleach. (When bleach is used to discharge on cotton fabric, it can be difficult to rinse and remove the last traces of chlorine, and if left in the fabric, chlorine will weaken the textile over time). Work with good ventilation and use a respirator or mask to avoid inhalation while it is in powder form. This is a Pro Chemical & Dye product; for MSDS sheets, visit www.prochemicalanddye.com.