Hth, 4 lb, pre-measured water soluble alkalinity up pods, easy to use pods make dosing simple & quick, keep your pool water comfortable for bathers & to protect pool surfaces & equipment from damage, the ph of pool water should be maintained between 7.2 & 7.8, help reduce ph drift & erratic changes when adjusting the ph by testing the total alkalinity each week & maintaining it between 60 & 120 ppm, raises ph levels, prevents corrosion of metal & plaster surfaces, prevents eye & skin irritation from pool water, compatible with salt water systems, contains eight 8 oz pods.