Coolant Strip effectively measures the pH level and glycol percent of engine coolant. Each bottle contains 100 test strips sealed in an aluminum container with a molecular sieve in the lid. This means you will receive absolutely fresh and accurate results on whether to change coolant or not. Having a test strip provides scientific proof of a needed service. Coolant left unchanged can lead to future corrosion, part failure and overheating. Be sure to use these to test the coolant (generally diluted 50/50) as it is in the vehicle. DO NOT test coolant in full concentrate without proper dilution.