Pack includes 100 x Blue Sparkle dip test strips that make caring for your ground pool/hot tub/spa simple and easy Measures chlorine, PH and alkalinity: Measures various quality levels of ground swimming pool/hot tub/spa water to indicate what chemicals are needed to prevent harmful bacteria entering your water Directions: Dip strip and remove immediately, hold strip level for 15 seconds, use simple-to-use guide on back of packet to read the results Quick and easy to use - simply dip the test strips into the water and check the results on the handy printed colour chart Quality of blue sparkle test strips are tested and approved as per the UK guidelines