The warmer works perfectly! I use it to warm glass. Depending on the size of the vial and wealth status you choose the setting on the rotary control. The water heats up and thus the contents of the vial. Stir a few times in between, then it goes even faster. One gets the feeling very quickly, which setting is required for the optimum temperature. The vial is kept also optimally warm. We have very hard water. The warmer is now one month in use, but still there is no lime has been deposited. Would I buy again immediately.