When they begin to "cool" after you have activate them, they will turn about as hard as a rock. Once this happens, boil a pot of water, cover your heart massager with a cloth/wash cloth and put it in the pain and let it boil for about 10 minutes or until the crystals have fully liquified. Once the solution inside the heart massager is completely liquified again, pull it out witha pair of tongs and set it aside on a dry cloth to cool. Once it is cooled again, you can store and reuse whenever you like! I have had several of these throughout the years and I will continue to buy them. I LOVE them and they work for just about anything and anyone! Even my kids love them. Hell, my husband keeps playin with mine and reusing them just to watch them "crystalize" after they are boiled back down. Drives me nuts cause he doesn't even use them, he just plays with the activation crystals lmao.

they don't vibrate.