The Hot Spring Spas Freshwater Spa Test Strips (part number 73687) will help you maintain a brilliantly clear, odor free spa water by testing for:TBr - Total BromineFCl - Free ChlorineAlk - AlkalinitypHHard - Total HardnessJust immerse strip, swirl 3 times, remove with pads face up, and compare against the chart on the bottle...it is that easy!Each bottle contains 50 test strips and we guarantee the expiration date is longer than 13 months.