they work good but all they are is ISo Alcohol and efferdent. the 420 formula is even the same color as the blue denture cleaner and Iso alcohol. if your gonna try one use the one with the scrubbing crystals or you could just spend about 3-5 bucks on a bottle of Iso alcohol and some efferdent. I find the iso alcohol is enough just soak it for about 6 hours then scrub with an old tooth brush.