Additive to restore and prolong whiteness - P&G Professional System 4 is a liquid whitening laundry additive. Helps to improve and maintain the whiteness impression of your white linen. Effective already at cold wash temperatures. Recommended to be used on white fabrics. Lightly coloured or pastel coloured items could be affected over repetitive washing. Most effective on cotton containing items but is compatible with synthetics. Fully compatible with the P&G Professional System line-up.