One step ahead with Lovibond®: DPD No.4 Evo contains only small amounts of potassium iodide. Water analysis at the pool has never been safer. The tablets can be used safely and, with their new formulation, provide the usual reliable results. As an indicator of pool hygiene, the DPD No.4 Evo tablets are indispensable for detecting the total chlorine content, especially in pool hygiene. Water analysis couldn't be quicker, simpler or more cost-effective. Together with the boric acid-free Green Chemistry, you are on the safe side with the potassium-reduced, enormously long-life DPD No.4 Evo reagents.