HTH 52040B Swimming Pool Care Shock Ultra, Swimming Pool Chemical, Cal Hypo Formula, 1lb (6 Pack)Brand: HTH Features: BENEFIT: Use this all in one powerhouse pool shock to increase chlorine levels, prevent bacteria, algae, stain, and scale, reduce skin and eye irritation, improve filtration, and soften your swimming pool water quickly and easily VISIBLY BRILLIANT SPARKLE: This Cal Hypo based formula sanitizes without adding cyanuric acid (CYA) to prevent overstabilization or chlorine lock VISIBLE BLUE ACTION: This built in feature lets you know