HTH Floater Tablet Swimming Pool Sanatizer 3 lb (Pack of 3)HTH makes pool care easier than ever with the pre filled chlorinating floater that helps sanitize and protect your pool water for up to 4 weeks (depending on the size of your pool). Simply set the adjustable dial to release the amount of chlorine thats right for your swimming pool size. This is a single use floater; once chlorine treatment has entirely dispersed, the floater will tip sideways. This floater is great for small in ground swimming pools