This efficiency insert is compatible with the VersaChlor I. Engineered to fit the most prevalent sizes of HMAC pools, the VersaChlor I leads the way to easy, cyanuric acid-free chlorination. This versatile chlorinator is the cornerstone of the calcium hypochlorite-based VersaChlor system, which gives pool service professionals more than just an advanced means of controlling harmful bacteria. It gives them—and everyone swimming in their pools—peace of mind, too.