Get fast and long-lasting relief from chest congestion with Mucinex Maximum Strength 12 Hour Extended-Release Tablets. Formulated with 1200 mg of guaifenesin, these bi-layer tablets are designed to provide immediate and extended release action to help thin and loosen mucus, making it easier to cough out. Whether you're dealing with a cold or chronic bronchitis, Mucinex ensures you stay comfortable for up to 12 hours.