Spa Sanitizing Dichlor Granules are a stabilized chlorine for sanitizing, shocking or super-chlorination. 99% Maximum strength, quick-dissolving. Active ingredient is sodium dichloro-s-triazinetrione dihydrate, 99%. Pre-dissolve by itself in a plastic bucket before adding to spa. 2 lb. container. Guaranteed to equal or outperform all other brands. Compare to Leisure Time Spa 56, SpaGuard Enhanced Shock, Spa Essentials Xtra.