Bowl Fresh Bicolor, blue plus bleach tablets fight stains with the Oxygen bleach. Cleans and deodorizes using Borax and detergents. Each tablet lasts up to 30 days. Prevents stains due to hard water, mineral substances, and lime scale. Safe for plumbing and septic systems. Completely dissolves in tank. Leaves no unsightly residue. Twin pack, 2 tablets, each 1.7 oz.