Is there a guarantee on the product?

Yes there is.This is on the http://mmsmiracle.com website, from the manufacturer of this MMS product.

"MMS Professional™ and Miracle Mineral Solution, Professional Grade™ are registered trademarks of PGL International, LLC. MMS Professional™ is the only professional grade MMS on the market, manufactured by an FDA certified GMP compliant Nutraceutical company and packaged with the utmost attention to safety and quality. Look for the MMS Professional™ label when using MMS or recommending to clients or customers."

This is a 4 oz bottle from PGL, factory sealed and guranteed to be 28% purity and gets the Jim Humble ok for purity.